{"id":145,"date":"2022-01-24T19:16:11","date_gmt":"2022-01-25T01:16:11","guid":{"rendered":"https:\/\/beta.nirvc.com\/blog\/?p=145"},"modified":"2023-01-25T16:05:18","modified_gmt":"2023-01-25T22:05:18","slug":"def-head-issues-everything-rvers-should-know-about-def-diesel-exhaust-fluid","status":"publish","type":"post","link":"https:\/\/www.nirvc.com\/blog\/def-head-issues-everything-rvers-should-know-about-def-diesel-exhaust-fluid\/","title":{"rendered":"DEF Head Issues? Everything RVers Should Know About DEF (Diesel Exhaust Fluid)."},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

The EPA has authored numerous regulations in vehicle\nemissions levels in an effort to improve the quality of the air we breathe. Increased\nregulations on diesel engine emissions are one area that has affected owners of\ndiesel powered motorhomes since 2003. The EPA 2007 regulations were a big\nchange requiring ultra-low sulphur diesel fuel and the addition of a Diesel\nParticulate Filter (DPF) to the exhaust system to reduce the level of soot in\nthe exhaust.<\/p>\n\n\n\n

The next big step was the Tier IV EPA 2010 emissions standards\nwhich took effect for the most part in model year 2011 motorhomes. These regulations\nwere a significant step in reducing pollutants from diesel engines and required\nsome major changes in the design of diesel engine emission systems. The prevalent\nmethod of achieving this was Cummins\u2019 implementation of Selective Catalytic\nReduction technology, commonly referred to as SCR. In addition to the Diesel\nParticulate Filter, SCR technology adds more complexity to the emissions system\nbut significantly lowers emissions below the EPA 2007 specifications.<\/p>\n\n\n\n

\"The
The SCR aftertreatment system sits above the muffler on the exhaust manifold side of the engine. <\/figcaption><\/figure>\n\n\n\n

The SCR system adds a decomposition reactor where Diesel\nExhaust Fluid (DEF) is injected into the exhaust stream where it forms ammonia\nvapor. The ammonia and nitrogen oxides in the exhaust flow together and pass\ninto the SCR Catalyst, where they react to form nitrogen and water vapor and\nreduce emissions to near-zero levels. SCR is aftertreatment technology so it\ndestroys these harmful emissions after combustion, which gives the engine\nmanufacturer the ability to fine tune their engines to produce maximum power,\nefficiency and fuel economy. Other than clean exhaust, the biggest impact upon\ncoach owners is the necessity of having to maintain a supply of  DEF in the coach\u2019s storage tank .<\/p>\n\n\n\n

However, changes to the EPA requirements in 2017 have resulted in a large number of DEF issues involving failed DEF sensor problems, resulting in forced engine shutdowns that have caused major downtime and cancelled trips for some owners. Before we get into the specifics of that and how to deal with it, let\u2019s first begin with a better understanding of the components of this system and DEF itself.<\/p>\n\n\n\n

\"Refilling
A shot of refilling a DEF tank from a 2-1\/2 gallon jug.<\/figcaption><\/figure>\n\n\n\n

What Is DEF?<\/strong><\/p>\n\n\n\n

Diesel Exhaust Fluid, or DEF, is a product designed\nexclusively for use in diesel engines using SCR emissions technology. It\u2019s basically\na non-hazardous solution of 32.5% urea and 67.5% water. It\u2019s clear and\ncolorless and has a slight smell of ammonia. DEF isn\u2019t something you can make\nyourself and engine manufacturers specify that any DEF used should by certified\nby the American Petroleum Institute (API), the same people who rate engine oils\nand other petroleum products. The API has a Diesel Exhaust Fluid Certification\nProgram that allows DEF producers to display the API certified label on their\nDEF packaging.<\/p>\n\n\n\n

The production of DEF is governed by the ISO 22241 standard.\nThis ensures that DEF is produced with an exacting 32.5% urea concentration.\nThis concentration is also designed to offer the lowest freezing temperature of\nDEF, 12o<\/sup> F. Contaminated fluid can damage SCR injectors and\ncatalysts so the level of impurities is limited to strict tolerances and DEF quality\nis also monitored. Urea used in manufacture of fertilizer is not allowed and\nonly distilled or deionized water may be used in DEF production. Even the\ncontainers are regulated by ISO 22241 because DEF is corrosive to carbon steel,\ncopper and aluminum so these containers may not be used. If your DEF container\nbears the API DEF Certification Mark, you can be assured that the product meets\nthe ISO 22241 standard and is safe to use in your vehicle.<\/p>\n\n\n\n

Just how much DEF your coach will use varies with the size\nof the engine and how hard you are working the engine. A common statement is\nthat DEF usage will equal 2% of your diesel fuel usage but this is just a\ngeneralization. Lighter RVs with small displacement engines that are driven\nmore leisurely have seen figures as low as 1.5% while larger heavy coaches with\nthe 15 liter X series engines have gone as high as 4%, depending on how hard\nyou are working the throttle and how much weight you are towing.<\/p>\n\n\n\n

\"Instrument
Instrument panels include a DEF level indicator as well, such as this common 4 LED bar graph display built into the fuel gauge.<\/figcaption><\/figure>\n\n\n\n

Handling DEF<\/strong><\/p>\n\n\n\n

DEF isn\u2019t overly difficult to handle but there are a few considerations\nto keep in mind. Bulk DEF is available at truck stops from dedicated DEF pumps\nlocated on the driver\u2019s side fuel island, oftentimes right next to the diesel\nfuel pump and located behind a rubber flap to prevent freezing in cold weather.\nDEF is also available in 2.5 gallon containers at auto parts stores, gas\nstations and most large retailers, such as Wal-Mart. As long as the container\nbears the API Certification Label it will meet the ISO 22241 standards so paying\nmore for certain name brands of DEF won\u2019t give you a better quality of DEF. It\u2019s\nonly ammonia water and doesn\u2019t contain additives like a sophisticated engine oil\nor high tech lubricant.<\/p>\n\n\n\n

DEF can evaporate if stored at high temperatures for\nprolonged periods because it is 67.5% water but field tests have shown that\nthere isn\u2019t a significant risk of evaporation from DEF tanks as long as you\nkeep your tank or container securely closed. DEF does have a shelf life of two\nyears but this can be reduced if the DEF is exposed to direct sunlight or if\nthe temperature remains above 86o<\/sup> F for sustained periods. DEF\npackaging does have an expiration date so keep that in mind if you plan on\nstocking up on DEF. Ideally your DEF should be stored in a location where\ntemperatures do not drop below freezing or exceed 85 degrees and will be\nconsumed within one year of purchase.<\/p>\n\n\n\n

\"DEF
The tanks are equipped with a blue filler cap that is appropriately labeled. The filler necks are designed to prevent the larger sized diesel fuel nozzles from accidentally being used in these tanks.<\/figcaption><\/figure>\n\n\n\n

DEF is always stored in its own tank and should never be put\ninto a diesel fuel tank nor is diesel fuel ever to be put into a DEF tank.\nFortunately there are a few safeguards in place to help prevent this from\nhappening. Diesel fuel nozzles are 0.87\u201d (22mm) in diameter while DEF nozzles\nare 0.75\u201d (19mm) in diameter so this should prevent anyone from accidentally inserting\na diesel fuel pump nozzle into a DEF tank. DEF tank caps are also blue in color\nto help identify them and separate them from diesel fuel tank caps. Diesel fuel\nis lighter than DEF and will float on the top of the DEF if it somehow managed\nto get into the tank but even a small amount of diesel fuel will damage the SCR\nsystem so do not run the engine. Instead, call a service center immediately and\ndo not drive the vehicle until they remove the diesel fuel from the DEF tank. <\/p>\n\n\n\n

On the other hand it is possible to insert the smaller DEF\nnozzle into a diesel fuel filler neck. If this happens, do not start the\nengine. DEF contains 67.5% water and this can have disastrous effects if mixed\nwith your diesel fuel, including exploding fuel injector tips. If this happens,\ndo not drive the vehicle and call for help to have the fuel system drained or\ncleaned to remove the DEF. Some bulk DEF pumps have magnetic switches built\ninto the nozzle to help prevent this from happening. The DEF tank has a magnet\nplaced in the filler neck that allows the DEF nozzle to open up and dispense\nDEF. The nozzle will not allow any flow without that magnet, such as when inserting\nthe DEF nozzle into a fuel tank filler. However, not every DEF pump has these magnetic\nswitches and neither do any of the 2.5 gallon jugs so you do need to pay close attention\nto which tank you are adding DEF to.<\/p>\n\n\n\n

DEF is not hazardous to handle but it can stain clothes if you spill any on your clothing. If you do spill any DEF on your clothing just wash it away with water. If you spill a small amount on the ground just rinse it with water or wipe it up with a paper towel or rag. Once any residue dries out it will turn to crystals, which can also be rinsed away with water. As mentioned earlier, DEF can be corrosive to carbon steel, copper or aluminum so if you spill any on those metals you may want to rinse that off fairly quickly.<\/p>\n\n\n\n

\"Pump
Pump DEF nozzles are stored behind a rubber flap to help keep it from being confused with diesel fuel nozzles and to help prevent it from freezing.<\/figcaption><\/figure>\n\n\n\n

DEF In Your Coach<\/strong><\/p>\n\n\n\n

Now that you know what DEF is let\u2019s take a look at how it is\nimplemented in your coach\u2019s emissions system. It begins by storing the DEF into\nthe typical 10 to 15 gallon polypropylene storage tank, which is required in\norder to prevent corrosion between the DEF and any metals. There are limits on\nthe length of the hoses that connect the DEF tank to the engine\u2019s emissions\nsystems so you\u2019ll find the tank located at the rear of the coach on a diesel\npusher chassis or at the front if a front engine vehicle such as a Super C or\nSprinter type chassis. Most side radiator chassis don\u2019t have enough room to\nplace the DEF tank on the driver\u2019s side of the coach so the tanks will be\nlocated on the curbside. Unfortunately, pump DEF at truck stops is always on\nthe driver\u2019s side to accommodate the driver\u2019s side DEF tanks on trucks so this\ndoesn\u2019t work well for an RV but in recent years the chassis manufacturers began\nto add additional driver\u2019s side DEF fills to make it more convenient for a\nmotorhome owner to use pump DEF when refueling. This does require moving the\ncoach forward after pumping fuel so that the pump nozzle can reach the\ndriver-side DEF filler at the rear but this a small inconvenience that is worthwhile\nbecause it allows you the ease of refilling your DEF tank and receiving the\nbulk pump price versus the higher cost of retail DEF jugs.<\/p>\n\n\n\n

DEF freezes at 12o<\/sup> F so it needs to be kept warm\nenough to allow tit to flow. The engine\u2019s cooling system passes heated engine\ncoolant through a heating element in the DEF tank to warm the DEF enough to\nallow this to happen. In extremely cold temperatures the DEF will not initially\nflow until the heat in the engine coolant has warmed up the DEF, which happens\nfairly fast, and the emissions controls will allow enough time for this to\nhappen without throwing an error code. Whenever the engine is shut down you may\nhear a buzzing noise coming from the rear of the coach. This is an electric\npurge pump that will run for approximately 60 seconds and will drain all of the\nDEF from the hoses and return it to the tank to prevent any freeze damage to\nthe lines and valves should the temperature drop below freezing. DEF expands\nabout 7% when frozen so you also need to keep a bit of air space above the DEF\nin the tank to allow for expansion during cold weather. The filler neck in DEF\ntanks is generally low enough to prevent over-filling but if your curbside tank\nalso has a second driver\u2019s side filler cap you will want to keep an eye on\nthis. Don\u2019t fill it all the way up or else the DEF won\u2019t have room to expand\nand damage will occur.<\/p>\n\n\n\n

\"DEF
The tanks are equipped with a blue filler cap that is appropriately labeled. The filler necks are designed to prevent the larger sized diesel fuel nozzles from accidentally being used in these tanks.<\/figcaption><\/figure>\n\n\n\n

The DEF is then sent to a dosing valve. This valve is\nelectronically controlled and sprays DEF into the decomposition chamber, which\nis located immediately after the Diesel Particulate Filter, and is both a filter\nand a catalyst that removes carbon particles from the exhaust gas and traps them\ninto a wall flow filter. At the same time nitric oxide in the exhaust gas is\nthen converted to nitrogen dioxide in the diesel oxidation catalyst. As the nitrogen\ndioxide flows through the wall-flow filter it reacts with the carbon to produce\ncarbon dioxide. As the exhaust flows out of the DPF and into the decomposition\nchamber a light mist of DEF is sprayed from the dosing valve into the decomposition\nchamber. It then forms ammonia through a series of chemical reactions.\nTogether, the NOx<\/sub> and ammonia pass from the decomposition reactor to\nthe SCR catalyst chamber where they react to form nitrogen and water vapor. The\nend result is exhaust with near zero emission levels.<\/p>\n\n\n\n

DEF is a critical component and without it your emissions\nsystem will not work. EPA requires that the vehicle emissions system must be\nfully operational at all times so certain safeguards are put in place to ensure\nthat you cannot continue to operate the vehicle without DEF. To ensure you know\nhow just much DEF is in your tank, a DEF gauge will be located on the\ninstrument panel. In most cases this is a series of four LED bars built within\nthe diesel fuel gauge. Four green bars will be displayed whenever the DEF tank\nis fuel. Three green bars indicate \u00be full while two green bars indicated \u00bd full\nand one green bar indicates \u00bc full. Once the level of DEF in the tank reaches\n10% that last green bar will turn to amber. Typically the LCD Information\nCenter on the instrument panel will display a \u201cLOW DEF\u201d warning in addition to\ndisplaying a warning icon on the panel. The vehicle will continue to operate\nnormally but if you have allowed the tank to get this low this is the point\nwhere you really need to consider how soon you can add more DEF to the tank. If\nyou continue on without adding, the amber LED bar will turn red when the DEF\nlevel in the tank reaches 5%. The Information Center will now display \u201cENGINE\nPERFORMANCE DERATE EMMINENT\u201d. You now have very little time left to add DEF\nbefore your engine derates. Once the level drops to 3% the display changes to \u201cENGINE\nPERFORMANCE DERATE ACTIVATED\u201d and your engine will be derated and there will be\na 25% reduction on its torque output. You\u2019ll still be able to limp off the road\nat reduced power but you\u2019ll still be burning DEF as you do so and the next step\nis the final step.<\/p>\n\n\n\n

\"DEF
The DEF filter is located at the rear of the DEF tank at the very bottom. Access to the DEF filter is gained by unscrewing the removable round filter cover.<\/figcaption><\/figure>\n\n\n\n

Once the DEF tank gets down to 0% the red LED bar remains\nilluminated and the Information Center now displays \u201cSPEED RESTRICTION ON. DEF\nREQUIRED\u201d. Engine torque will now be limited to 60% and the vehicle speed will\nbe limited to 5 MPH. That\u2019s enough to pull off to the side of the road but you\nwill need to fill the DEF tank to at least 10% in order to drive to a location\nwhere you can top off the tank. Carrying a 2.5 gallon jug or two of DEF as a\nsafety precaution can be a wise choice, even if you normally refill with pump\nDEF at truck stops.<\/p>\n\n\n\n

DEF systems aren\u2019t high maintenance. If you store your coach\nover a longer periods of time or run the engine for very short and infrequent\nruns your DEF can get old and beyond its shelf life. In that case the best\npractice is to drain the DEF from the tank and replace it with fresh every\nyear. There is a DEF filter located near the bottom of the DEF tank. This\nfilter should be replaced every 200,000 miles or two years, whichever comes\nfirst. The filter is easily removed with a 1-1\/16\u201d 12-point socket and\nextension. If the cap wasn\u2019t excessively tightened you may be able to remove\nthe DEF filter cap with a channel-lock pliers without damaging the cap. The\nfilter is at the base of the tank so you\u2019ll be looking up at it. Just be sure\nthat you are off to one side when you remove it because a bit of DEF will\ndribble out of the filter housing. The actual Cummins DEF filter is a small cartridge\nfilter and comes with a small tool to help yank the filter out of the housing.\nThis filter is sometimes forgotten by owners when servicing their chassis but a\nplugged or restricted filter can lead to a failed DEF pump, which is a more\nexpensive repair, so do not neglect this filter.<\/p>\n\n\n\n

\"Cummins
The Cummins DEF filter includes a small removal tool to aide in removing the filter from the housing.<\/figcaption><\/figure>\n\n\n\n

DEF Sensor Issues<\/strong><\/p>\n\n\n\n

The DEF head are inserted into the top of the DEF tank. The head consists of the DEF pickup tube, the engine coolant heater tube and the DEF sensor. The sensor was originally designed to sense the level of DEF in the tank but in 2016 the EPA mandated that new sensor designs were required that also detected the concentration level of DEF to ensure that owners weren\u2019t diluting their DEF with water and rendering the emissions system ineffective. These sensors showed up mainly in the 2017 model year coaches. Unfortunately, while the original 2016 and prior year sensors were trouble-free, these new sensors began failing at a rapid rate. In particular, the sensors used in the Spartan chassis had the most failures. These sensors were made by Shaw and had issues where the electronic circuit board had failed, which was determined to be heat related due to the close proximity of the engine\u2019s exhaust system as well as the fact that hot engine coolant was constantly circulating through the DEF head.<\/p>\n\n\n\n

When the sensor failed the engine would shut down, typically\ndisplaying one of the following fault codes showing abnormal update rates:<\/p>\n\n\n\n

            SPN 3364\nFMI 9 (Cummins Fault Code 3868) \u2013DEF quality<\/p>\n\n\n\n

            SPN 1761\nFMI 9 (Cummins Fault Code 4677) \u2013 DEF tank level<\/p>\n\n\n\n

            SPN 3031\nFMI 9 (Cummins Fault Code 4572) \u2013 DEF tank temperature<\/p>\n\n\n\n

These codes were designed to detect weak DEF, low DEF level\nor DEF that had been overheated in the tank. If the sensor chip fails any one\nof these fault codes may appear, even though there is nothing wrong with the\nDEF itself. But the faulty sensor will derate and eventually shut down your\nengine.<\/p>\n\n\n\n

The Shaw sensors were revised over time but the newer\nrevisions still had issues and as of generation 6 there were still continuing\nfailures and many RVs were sidelined due to a lack of replacement sensors, mainly\ndue to the electronic chip shortage affecting the automotive industry in\ngeneral in addition to the time involved in developing a new chip revision. The\nEPA began working with Cummins to allow an industry-wide software solution to\nallow vehicles with failed sensors to operate temporarily until replacement\nparts are available. But the EPA and Cummins haven\u2019t yet determined how soon\nthis software update will be available so a few RV owners simply took the initiative\nand developed the software to create a DEF sensor simulator.<\/p>\n\n\n\n

This simulator was a small electronic piece that is used to communicate\nwith the ECM in place of the faulty DEF sensor. You simply unplug the 4 conductor\nharness from the DEF sensor and connect it to the simulator. The simulator is\ndesigned to provide normal readings to the engine\u2019s ECM so that it can continue\nto operate without shutting down by transmitting normal readings to the engine\u2019s\nECM. The caveat to this simulator is that you no longer have any information as\nto the level of DEF in the tank so you needed to physically monitor the level\nof DEF in the tank. However, it allowed the owner to operate the vehicle and\ncomplete the trip rather than be sidelined. The system will still meter DEF to\nthe SCR so the pollution abatement portion of your emissions system will still operate\nas designed.<\/p>\n\n\n\n

The simulator is a DIY home build operation if you are handy\nwith electronics. Check out https:\/\/defsim.myervin.com\/def-sensor-simulator-quick-build<\/a>\nfor instructions on how to build this if you are interested. The software is\noffered free of charge. You just have to buy the components you need, download\nthe free software to its chip and build it yourself. While it is illegal to modify\na vehicle\u2019s emissions system in an effort to defeat the DEF system, this simulator\ndoes not defeat the emissions operation so is therefore not illegal. It\u2019s\nstrictly a temporary way to operate your vehicle until it can be properly\nrepaired whole still retaining full emissions capability.<\/p>\n\n\n\n

Shaw\u2019s latest generation 7 sensors began to arrive around May of 2021 and as of this writing there don\u2019t seem to be failures with these sensors so it\u2019s quite possible that this issue is no longer a concern. However, having a simulator on hand may just be the insurance you need to keep your motorhome operating should a failure occur.<\/p>\n\n\n\n

<\/div>\n\n\n\n
\"National
Mark Quasius is the founder of RVtechMag.com, the past Midwest editor of RV Magazine, writes for numerous RV-related publications and a regular Contributor to FMCA\u2019s Family RVing Magazine. Mark and his wife Leann travel in their 2016 Entegra Cornerstone.<\/em><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

The EPA has authored numerous regulations in vehicle emissions levels in an effort to improve the quality of the air we breathe. Increased regulations on diesel engine emissions are one area that has affected owners of diesel powered motorhomes since 2003. The EPA 2007 regulations were a big change requiring ultra-low sulphur diesel fuel and … Continue reading DEF Head Issues? Everything RVers Should Know About DEF (Diesel Exhaust Fluid).<\/span><\/a><\/p>\n","protected":false},"author":5,"featured_media":151,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"off","_et_pb_old_content":"\n

\"\"<\/figure>\n\n\n\n

The EPA has authored numerous regulations in vehicle\nemissions levels in an effort to improve the quality of the air we breathe. Increased\nregulations on diesel engine emissions are one area that has affected owners of\ndiesel powered motorhomes since 2003. The EPA 2007 regulations were a big\nchange requiring ultra-low sulphur diesel fuel and the addition of a Diesel\nParticulate Filter (DPF) to the exhaust system to reduce the level of soot in\nthe exhaust.<\/p>\n\n\n\n

The next big step was the Tier IV EPA 2010 emissions standards\nwhich took effect for the most part in model year 2011 motorhomes. These regulations\nwere a significant step in reducing pollutants from diesel engines and required\nsome major changes in the design of diesel engine emission systems. The prevalent\nmethod of achieving this was Cummins\u2019 implementation of Selective Catalytic\nReduction technology, commonly referred to as SCR. In addition to the Diesel\nParticulate Filter, SCR technology adds more complexity to the emissions system\nbut significantly lowers emissions below the EPA 2007 specifications.<\/p>\n\n\n\n

\"The
The SCR aftertreatment system sits above the muffler on the exhaust manifold side of the engine. <\/figcaption><\/figure>\n\n\n\n

The SCR system adds a decomposition reactor where Diesel\nExhaust Fluid (DEF) is injected into the exhaust stream where it forms ammonia\nvapor. The ammonia and nitrogen oxides in the exhaust flow together and pass\ninto the SCR Catalyst, where they react to form nitrogen and water vapor and\nreduce emissions to near-zero levels. SCR is aftertreatment technology so it\ndestroys these harmful emissions after combustion, which gives the engine\nmanufacturer the ability to fine tune their engines to produce maximum power,\nefficiency and fuel economy. Other than clean exhaust, the biggest impact upon\ncoach owners is the necessity of having to maintain a supply of  DEF in the coach\u2019s storage tank .<\/p>\n\n\n\n

However, changes to the EPA requirements in 2017 have resulted\nin a large number of issues involving failed DEF sensors, resulting in forced\nengine shutdowns that have caused major downtime and cancelled trips for some owners.\nBefore we get into the specifics of that and how to deal with it, let\u2019s first\nbegin with a better understanding of the components of this system and DEF\nitself.<\/p>\n\n\n\n

\"Refilling
A shot of refilling a DEF tank from a 2-1\/2 gallon jug.<\/figcaption><\/figure>\n\n\n\n

What Is DEF?<\/strong><\/p>\n\n\n\n

Diesel Exhaust Fluid, or DEF, is a product designed\nexclusively for use in diesel engines using SCR emissions technology. It\u2019s basically\na non-hazardous solution of 32.5% urea and 67.5% water. It\u2019s clear and\ncolorless and has a slight smell of ammonia. DEF isn\u2019t something you can make\nyourself and engine manufacturers specify that any DEF used should by certified\nby the American Petroleum Institute (API), the same people who rate engine oils\nand other petroleum products. The API has a Diesel Exhaust Fluid Certification\nProgram that allows DEF producers to display the API certified label on their\nDEF packaging.<\/p>\n\n\n\n

The production of DEF is governed by the ISO 22241 standard.\nThis ensures that DEF is produced with an exacting 32.5% urea concentration.\nThis concentration is also designed to offer the lowest freezing temperature of\nDEF, 12o<\/sup> F. Contaminated fluid can damage SCR injectors and\ncatalysts so the level of impurities is limited to strict tolerances and DEF quality\nis also monitored. Urea used in manufacture of fertilizer is not allowed and\nonly distilled or deionized water may be used in DEF production. Even the\ncontainers are regulated by ISO 22241 because DEF is corrosive to carbon steel,\ncopper and aluminum so these containers may not be used. If your DEF container\nbears the API DEF Certification Mark, you can be assured that the product meets\nthe ISO 22241 standard and is safe to use in your vehicle.<\/p>\n\n\n\n

Just how much DEF your coach will use varies with the size\nof the engine and how hard you are working the engine. A common statement is\nthat DEF usage will equal 2% of your diesel fuel usage but this is just a\ngeneralization. Lighter RVs with small displacement engines that are driven\nmore leisurely have seen figures as low as 1.5% while larger heavy coaches with\nthe 15 liter X series engines have gone as high as 4%, depending on how hard\nyou are working the throttle and how much weight you are towing.<\/p>\n\n\n\n

\"Instrument
Instrument panels include a DEF level indicator as well, such as this common 4 LED bar graph display built into the fuel gauge.<\/figcaption><\/figure>\n\n\n\n

Handling DEF<\/strong><\/p>\n\n\n\n

DEF isn\u2019t overly difficult to handle but there are a few considerations\nto keep in mind. Bulk DEF is available at truck stops from dedicated DEF pumps\nlocated on the driver\u2019s side fuel island, oftentimes right next to the diesel\nfuel pump and located behind a rubber flap to prevent freezing in cold weather.\nDEF is also available in 2.5 gallon containers at auto parts stores, gas\nstations and most large retailers, such as Wal-Mart. As long as the container\nbears the API Certification Label it will meet the ISO 22241 standards so paying\nmore for certain name brands of DEF won\u2019t give you a better quality of DEF. It\u2019s\nonly ammonia water and doesn\u2019t contain additives like a sophisticated engine oil\nor high tech lubricant.<\/p>\n\n\n\n

DEF can evaporate if stored at high temperatures for\nprolonged periods because it is 67.5% water but field tests have shown that\nthere isn\u2019t a significant risk of evaporation from DEF tanks as long as you\nkeep your tank or container securely closed. DEF does have a shelf life of two\nyears but this can be reduced if the DEF is exposed to direct sunlight or if\nthe temperature remains above 86o<\/sup> F for sustained periods. DEF\npackaging does have an expiration date so keep that in mind if you plan on\nstocking up on DEF. Ideally your DEF should be stored in a location where\ntemperatures do not drop below freezing or exceed 85 degrees and will be\nconsumed within one year of purchase.<\/p>\n\n\n\n

\"DEF
The tanks are equipped with a blue filler cap that is appropriately labeled. The filler necks are designed to prevent the larger sized diesel fuel nozzles from accidentally being used in these tanks.<\/figcaption><\/figure>\n\n\n\n

DEF is always stored in its own tank and should never be put\ninto a diesel fuel tank nor is diesel fuel ever to be put into a DEF tank.\nFortunately there are a few safeguards in place to help prevent this from\nhappening. Diesel fuel nozzles are 0.87\u201d (22mm) in diameter while DEF nozzles\nare 0.75\u201d (19mm) in diameter so this should prevent anyone from accidentally inserting\na diesel fuel pump nozzle into a DEF tank. DEF tank caps are also blue in color\nto help identify them and separate them from diesel fuel tank caps. Diesel fuel\nis lighter than DEF and will float on the top of the DEF if it somehow managed\nto get into the tank but even a small amount of diesel fuel will damage the SCR\nsystem so do not run the engine. Instead, call a service center immediately and\ndo not drive the vehicle until they remove the diesel fuel from the DEF tank. <\/p>\n\n\n\n

On the other hand it is possible to insert the smaller DEF\nnozzle into a diesel fuel filler neck. If this happens, do not start the\nengine. DEF contains 67.5% water and this can have disastrous effects if mixed\nwith your diesel fuel, including exploding fuel injector tips. If this happens,\ndo not drive the vehicle and call for help to have the fuel system drained or\ncleaned to remove the DEF. Some bulk DEF pumps have magnetic switches built\ninto the nozzle to help prevent this from happening. The DEF tank has a magnet\nplaced in the filler neck that allows the DEF nozzle to open up and dispense\nDEF. The nozzle will not allow any flow without that magnet, such as when inserting\nthe DEF nozzle into a fuel tank filler. However, not every DEF pump has these magnetic\nswitches and neither do any of the 2.5 gallon jugs so you do need to pay close attention\nto which tank you are adding DEF to.<\/p>\n\n\n\n

DEF is not hazardous to handle but it can stain clothes if you spill any on your clothing. If you do spill any DEF on your clothing just wash it away with water. If you spill a small amount on the ground just rinse it with water or wipe it up with a paper towel or rag. Once any residue dries out it will turn to crystals, which can also be rinsed away with water. As mentioned earlier, DEF can be corrosive to carbon steel, copper or aluminum so if you spill any on those metals you may want to rinse that off fairly quickly.<\/p>\n\n\n\n

\"Pump
Pump DEF nozzles are stored behind a rubber flap to help keep it from being confused with diesel fuel nozzles and to help prevent it from freezing.<\/figcaption><\/figure>\n\n\n\n

DEF In Your Coach<\/strong><\/p>\n\n\n\n

Now that you know what DEF is let\u2019s take a look at how it is\nimplemented in your coach\u2019s emissions system. It begins by storing the DEF into\nthe typical 10 to 15 gallon polypropylene storage tank, which is required in\norder to prevent corrosion between the DEF and any metals. There are limits on\nthe length of the hoses that connect the DEF tank to the engine\u2019s emissions\nsystems so you\u2019ll find the tank located at the rear of the coach on a diesel\npusher chassis or at the front if a front engine vehicle such as a Super C or\nSprinter type chassis. Most side radiator chassis don\u2019t have enough room to\nplace the DEF tank on the driver\u2019s side of the coach so the tanks will be\nlocated on the curbside. Unfortunately, pump DEF at truck stops is always on\nthe driver\u2019s side to accommodate the driver\u2019s side DEF tanks on trucks so this\ndoesn\u2019t work well for an RV but in recent years the chassis manufacturers began\nto add additional driver\u2019s side DEF fills to make it more convenient for a\nmotorhome owner to use pump DEF when refueling. This does require moving the\ncoach forward after pumping fuel so that the pump nozzle can reach the\ndriver-side DEF filler at the rear but this a small inconvenience that is worthwhile\nbecause it allows you the ease of refilling your DEF tank and receiving the\nbulk pump price versus the higher cost of retail DEF jugs.<\/p>\n\n\n\n

DEF freezes at 12o<\/sup> F so it needs to be kept warm\nenough to allow tit to flow. The engine\u2019s cooling system passes heated engine\ncoolant through a heating element in the DEF tank to warm the DEF enough to\nallow this to happen. In extremely cold temperatures the DEF will not initially\nflow until the heat in the engine coolant has warmed up the DEF, which happens\nfairly fast, and the emissions controls will allow enough time for this to\nhappen without throwing an error code. Whenever the engine is shut down you may\nhear a buzzing noise coming from the rear of the coach. This is an electric\npurge pump that will run for approximately 60 seconds and will drain all of the\nDEF from the hoses and return it to the tank to prevent any freeze damage to\nthe lines and valves should the temperature drop below freezing. DEF expands\nabout 7% when frozen so you also need to keep a bit of air space above the DEF\nin the tank to allow for expansion during cold weather. The filler neck in DEF\ntanks is generally low enough to prevent over-filling but if your curbside tank\nalso has a second driver\u2019s side filler cap you will want to keep an eye on\nthis. Don\u2019t fill it all the way up or else the DEF won\u2019t have room to expand\nand damage will occur.<\/p>\n\n\n\n

\"DEF
The tanks are equipped with a blue filler cap that is appropriately labeled. The filler necks are designed to prevent the larger sized diesel fuel nozzles from accidentally being used in these tanks.<\/figcaption><\/figure>\n\n\n\n

The DEF is then sent to a dosing valve. This valve is\nelectronically controlled and sprays DEF into the decomposition chamber, which\nis located immediately after the Diesel Particulate Filter, and is both a filter\nand a catalyst that removes carbon particles from the exhaust gas and traps them\ninto a wall flow filter. At the same time nitric oxide in the exhaust gas is\nthen converted to nitrogen dioxide in the diesel oxidation catalyst. As the nitrogen\ndioxide flows through the wall-flow filter it reacts with the carbon to produce\ncarbon dioxide. As the exhaust flows out of the DPF and into the decomposition\nchamber a light mist of DEF is sprayed from the dosing valve into the decomposition\nchamber. It then forms ammonia through a series of chemical reactions.\nTogether, the NOx<\/sub> and ammonia pass from the decomposition reactor to\nthe SCR catalyst chamber where they react to form nitrogen and water vapor. The\nend result is exhaust with near zero emission levels.<\/p>\n\n\n\n

DEF is a critical component and without it your emissions\nsystem will not work. EPA requires that the vehicle emissions system must be\nfully operational at all times so certain safeguards are put in place to ensure\nthat you cannot continue to operate the vehicle without DEF. To ensure you know\nhow just much DEF is in your tank, a DEF gauge will be located on the\ninstrument panel. In most cases this is a series of four LED bars built within\nthe diesel fuel gauge. Four green bars will be displayed whenever the DEF tank\nis fuel. Three green bars indicate \u00be full while two green bars indicated \u00bd full\nand one green bar indicates \u00bc full. Once the level of DEF in the tank reaches\n10% that last green bar will turn to amber. Typically the LCD Information\nCenter on the instrument panel will display a \u201cLOW DEF\u201d warning in addition to\ndisplaying a warning icon on the panel. The vehicle will continue to operate\nnormally but if you have allowed the tank to get this low this is the point\nwhere you really need to consider how soon you can add more DEF to the tank. If\nyou continue on without adding, the amber LED bar will turn red when the DEF\nlevel in the tank reaches 5%. The Information Center will now display \u201cENGINE\nPERFORMANCE DERATE EMMINENT\u201d. You now have very little time left to add DEF\nbefore your engine derates. Once the level drops to 3% the display changes to \u201cENGINE\nPERFORMANCE DERATE ACTIVATED\u201d and your engine will be derated and there will be\na 25% reduction on its torque output. You\u2019ll still be able to limp off the road\nat reduced power but you\u2019ll still be burning DEF as you do so and the next step\nis the final step.<\/p>\n\n\n\n

\"DEF
The DEF filter is located at the rear of the DEF tank at the very bottom. Access to the DEF filter is gained by unscrewing the removable round filter cover.<\/figcaption><\/figure>\n\n\n\n

Once the DEF tank gets down to 0% the red LED bar remains\nilluminated and the Information Center now displays \u201cSPEED RESTRICTION ON. DEF\nREQUIRED\u201d. Engine torque will now be limited to 60% and the vehicle speed will\nbe limited to 5 MPH. That\u2019s enough to pull off to the side of the road but you\nwill need to fill the DEF tank to at least 10% in order to drive to a location\nwhere you can top off the tank. Carrying a 2.5 gallon jug or two of DEF as a\nsafety precaution can be a wise choice, even if you normally refill with pump\nDEF at truck stops.<\/p>\n\n\n\n

DEF systems aren\u2019t high maintenance. If you store your coach\nover a longer periods of time or run the engine for very short and infrequent\nruns your DEF can get old and beyond its shelf life. In that case the best\npractice is to drain the DEF from the tank and replace it with fresh every\nyear. There is a DEF filter located near the bottom of the DEF tank. This\nfilter should be replaced every 200,000 miles or two years, whichever comes\nfirst. The filter is easily removed with a 1-1\/16\u201d 12-point socket and\nextension. If the cap wasn\u2019t excessively tightened you may be able to remove\nthe DEF filter cap with a channel-lock pliers without damaging the cap. The\nfilter is at the base of the tank so you\u2019ll be looking up at it. Just be sure\nthat you are off to one side when you remove it because a bit of DEF will\ndribble out of the filter housing. The actual Cummins DEF filter is a small cartridge\nfilter and comes with a small tool to help yank the filter out of the housing.\nThis filter is sometimes forgotten by owners when servicing their chassis but a\nplugged or restricted filter can lead to a failed DEF pump, which is a more\nexpensive repair, so do not neglect this filter.<\/p>\n\n\n\n

\"Cummins
The Cummins DEF filter includes a small removal tool to aide in removing the filter from the housing.<\/figcaption><\/figure>\n\n\n\n

DEF Sensor Issues<\/strong><\/p>\n\n\n\n

The DEF head is inserted into the top of the DEF tank. The\nhead consists of the DEF pickup tube, the engine coolant heater tube and the\nDEF sensor. The sensor was originally designed to sense the level of DEF in the\ntank but in 2016 the EPA mandated that new sensor designs were required that\nalso detected the concentration level of DEF to ensure that owners weren\u2019t\ndiluting their DEF with water and rendering the emissions system ineffective.\nThese sensors showed up mainly in the 2017 model year coaches. Unfortunately,\nwhile the original 2016 and prior year sensors were trouble-free, these new\nsensors began failing at a rapid rate. In particular, the sensors used in the\nSpartan chassis had the most failures. These sensors were made by Shaw and had\nissues where the electronic circuit board had failed, which was determined to\nbe heat related due to the close proximity of the engine\u2019s exhaust system as\nwell as the fact that hot engine coolant was constantly circulating through the\nDEF head.<\/p>\n\n\n\n

When the sensor failed the engine would shut down, typically\ndisplaying one of the following fault codes showing abnormal update rates:<\/p>\n\n\n\n

            SPN 3364\nFMI 9 (Cummins Fault Code 3868) \u2013DEF quality<\/p>\n\n\n\n

            SPN 1761\nFMI 9 (Cummins Fault Code 4677) \u2013 DEF tank level<\/p>\n\n\n\n

            SPN 3031\nFMI 9 (Cummins Fault Code 4572) \u2013 DEF tank temperature<\/p>\n\n\n\n

These codes were designed to detect weak DEF, low DEF level\nor DEF that had been overheated in the tank. If the sensor chip fails any one\nof these fault codes may appear, even though there is nothing wrong with the\nDEF itself. But the faulty sensor will derate and eventually shut down your\nengine.<\/p>\n\n\n\n

The Shaw sensors were revised over time but the newer\nrevisions still had issues and as of generation 6 there were still continuing\nfailures and many RVs were sidelined due to a lack of replacement sensors, mainly\ndue to the electronic chip shortage affecting the automotive industry in\ngeneral in addition to the time involved in developing a new chip revision. The\nEPA began working with Cummins to allow an industry-wide software solution to\nallow vehicles with failed sensors to operate temporarily until replacement\nparts are available. But the EPA and Cummins haven\u2019t yet determined how soon\nthis software update will be available so a few RV owners simply took the initiative\nand developed the software to create a DEF sensor simulator.<\/p>\n\n\n\n

This simulator was a small electronic piece that is used to communicate\nwith the ECM in place of the faulty DEF sensor. You simply unplug the 4 conductor\nharness from the DEF sensor and connect it to the simulator. The simulator is\ndesigned to provide normal readings to the engine\u2019s ECM so that it can continue\nto operate without shutting down by transmitting normal readings to the engine\u2019s\nECM. The caveat to this simulator is that you no longer have any information as\nto the level of DEF in the tank so you needed to physically monitor the level\nof DEF in the tank. However, it allowed the owner to operate the vehicle and\ncomplete the trip rather than be sidelined. The system will still meter DEF to\nthe SCR so the pollution abatement portion of your emissions system will still operate\nas designed.<\/p>\n\n\n\n

The simulator is a DIY home build operation if you are handy\nwith electronics. Check out https:\/\/defsim.myervin.com\/def-sensor-simulator-quick-build<\/a>\nfor instructions on how to build this if you are interested. The software is\noffered free of charge. You just have to buy the components you need, download\nthe free software to its chip and build it yourself. While it is illegal to modify\na vehicle\u2019s emissions system in an effort to defeat the DEF system, this simulator\ndoes not defeat the emissions operation so is therefore not illegal. It\u2019s\nstrictly a temporary way to operate your vehicle until it can be properly\nrepaired whole still retaining full emissions capability.<\/p>\n\n\n\n

Shaw\u2019s latest generation 7 sensors began to arrive around\nMay of 2021 and as of this writing there don\u2019t seem to be failures with these\nsensors so it\u2019s quite possible that this issue is no longer a concern. However,\nhaving a simulator on hand may just be the insurance you need to keep your\nmotorhome operating should a failure occur.<\/p>\n","_et_gb_content_width":"","footnotes":""},"categories":[8,12],"tags":[37,34,35,36,38,24,39,27],"class_list":["post-145","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-rv-lifestyle","category-rv-tips-tricks","tag-class-a-rv","tag-def","tag-def-head","tag-diesel-engine","tag-diesel-pusher","tag-rv-education","tag-rv-engine-maintenance","tag-rv-pro-tips"],"acf":[],"yoast_head":"\nDEF Heads & DEF Problems: What Do I Need to Know? | NIRVC<\/title>\n<meta name=\"description\" content=\"Learn everything you need to know about DEF Head Failure, Issues, System Problems & more. 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