Entertainment Systems For RVs

Entertainment systems are key features on an RV

Go through any motorhome on a dealer’s lot and you’ll find advanced systems that rival anything found in a home. But RV entertainment systems have changed over the years…

What began in the early days as a small portable 12 volt television with rabbit ears has now evolved into a sophisticated system featuring numerous digital input sources, such as Blu-ray players, satellite TV, streaming video and large screen LED TVs with surround sound systems. VCRs have been replaced by DVRs, DVDs by Blu-ray, and even 1080P HD signals are being supplemented by 4K UHD. Even over-the-air free broadcast TV has changed. The old analog VHF TV channels have been upgraded to digital UHF channels, with multiple channels with different programming coming from a single TV station. The Internet has made massive strides as technology and bandwidth have improved and streaming services, such as Netflix and Hulu, are quickly becoming the next great thing.

Delivery Methods

The content that you desire to view is meaningless unless you can get it delivered to your RV. While cable TV and Internet may be fine for a sticks-and-bricks home, it’s not going to work in an RV that is mobile.

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A Winegard Sensar batwing style crank-up antenna.

Over-the-air free broadcast TV is always available as long as you are in range of a broadcast TV station’s tower and the original crank-up batwing TV antenna still works today. You crank it up to raise the antenna and then rotate it to point in the direction of the TV station. Adding a Wingman booster will help pull in stronger UHF signals. The “height is might” analogy applies here. The downside is that you need to manually raise and rotate it and you’ll need to remember to retract it before you move, or else it will be damaged while driving.

National Indoor RV Centers blog Mark Quasius Entertainment Systems for Class A Class B and Class RVs and motorhomes

The Winegard Rayzar Automatic is an automatic over-the-air antenna.

A more convenient system is Winegard’s Rayzar Automatic, which is a round enclosure with a digital antenna that rotates automatically to find the stations that are within range – simply by pressing a button. This antenna also includes a built-in amplifier and, while the batwing with Wingman does pull in stronger signals, the Rayzar Automatic isn’t very far behind and you don’t have to worry about having to retract it before traveling.

The next big thing to show up in RVs was satellite TV. With a dish aimed at the southern sky, one can receive paid content from providers such as DirecTV or DISH Network. Different plans are available and the cost rises as the number of channels increases. These units can use a portable tripod-based dish which requires manual aiming, or can be fed through an in-motion dome or via an automatic roof-mounted dish such as the Winegard Trav’ler or RF Mogul’s excellent Eagle dish. Just power up the system and it will search for the satellite and lock on automatically.

National Indoor RV Centers blog Mark Quasius Entertainment Systems for Class A Class B and Class RVs and motorhomes

A portable tripod satellite dish may be necessary if tree branches obscure a clear view to the satellite.

The manual dish mounts to a tripod and requires a bit of work to set up and adjust to find the satellite. Various apps exist to show you the correct azimuth, elevation and skew so that you can set the dish to these approximate settings and then use a signal meter to analyze the signal level as you fine tune or dither the dish to achieve the strongest signal. While this takes work, it may be necessary if you plan on staying in one place for a while where the tree coverage prevents a rooftop mounted dish from getting a clear signal from the satellite.

The satellites are located near the equator in a geosynchronous orbit, so your dish needs to be aimed towards the southern sky to find the satellite. Azimuth and elevation will change as you move around the country and anything that blocks the signal, such as trees, will prevent access to the satellite. Even storm clouds will make a difference and rain fade is a common occurrence if storm clouds come rolling in.

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The King-Dome is one example of an in-motion satellite dish.

Automatic domes were available from suppliers such as KVH, Winegard and King Controls that eliminated the manual setup procedures and were popular at first, but by 2000 had fallen in favor for a number of reasons. First, DirecTV began making more HD content available. This necessitated moving HD content from the lower bandwidth KU band to the higher KA band. The in-motion dishes weren’t capable of receiving the KA band, which required a triple LNB oval dish. There just wasn’t enough room inside the dome to place a triple LNB dish. In fact, the dome required a fairly small dish that didn’t equal the signal strength of a large tripod or roof mounted dish. This created a weaker signal which was really susceptible to rain fade, especially if there was any morning dew or snow on the dome.

National Indoor RV Centers blog Mark Quasius Entertainment Systems for Class A Class B and Class RVs and motorhomes

The Winegard Trav’ler automatic satellite dish is an automatic deploying dish.

Fortunately, Winegard introduced the Trav’ler automatic dish. This dish could be set up for DirecTV or DISH Network use. This rooftop-mounted dish automatically deployed with the push of a button, searched for the satellite and locked onto the signal. When ready to travel, a second button push on the controller caused the dish to fold up flat into the storage position for travel. RF Mogul also came out with the Eagle automatic dish which was a superior unit to the Winegard. These units provided satellite TV to any RV and were the number one choice – at least until streaming appeared.

National Indoor RV Centers blog Mark Quasius Entertainment Systems for Class A Class B and Class RVs and motorhomes

The Winegard ConnecT 2.0 can connect to cellular or campground Wi-Fi sources and will provide internet access via an internal router to any connected device in the RV.

At home, nearly everyone has high speed Internet and, as streaming services first began to offer entertainment content, many of the old standbys started to decline in popularity. Satellite TV subscription costs steadily rose every year, causing its popularity to decline. The RV industry was only a small percentage of the market, so issues such as portability of local channels while traveling also became a hassle. Gradually the entire world began to embrace streaming entertainment rather than cable or satellite TV. It began with services such as Netflix, with movie content that virtually put DVD rental stores out of business. Soon, services such as Hulu began to offer much of what was currently available on satellite and cable TV. Once other content providers jumped in with their own services, the “cut the cable” rush was in full swing. Now it was just up to the RV owner to figure out how to get this streaming content into their motorhome. 

Streaming requires a high speed Internet connection. The early days of dial-up were fine for accessing email or viewing the weather, but too slow for streaming content. Campground Wi-Fi was the next step but as everyone got on the streaming bandwagon, the bandwidth demand exceeded the ability of the campground to supply enough bandwidth. So limitations were imposed by the campgrounds as Wi-Fi service became spotty. 

As cell towers began to appear everywhere, this offered an alternative. And as signals improved to 3G, 4GLTE and now 5G, the ability to handle larger data (such as streaming video) improved. It was now up to the cell companies to provide packages that were capable of handling streaming video. In essence, the cell companies were now getting the monthly premiums that were previously going to the cable and satellite companies. But because the Internet was so popular anyway, the subscribers were at least getting more for their money by not having to pay both a satellite TV bill to one supplier, and a cellular internet service bill to another.

To get a cellular or Wi-Fi feed into your motorhome, you would need a router to set up a personal network as well as an access device such as an air card, Jetpack or SIM card that plugs into a wireless router. One popular device for motorhome owners is the Winegard ConnecT 2.0. This dome mounts on the roof of the RV and can connect to a campground Wi-Fi source or to an AT&T or Verizon cell service via a SIM card. It then creates a personal wireless network within your RV. This lets you log into the wireless router with the same login information every time – on your phones, iPads, laptops or connected coach systems, regardless of where the incoming source is coming from.

One other source for streaming video is satellite Internet, such as Hughes Net. This is a pricey option and has limits on monthly bandwidth usage. It has long latency issues because the signal needs to travel 22,000 miles up to a satellite and back again. This makes it a bad choice for online gaming but isn’t a problem for streaming video such as movies where constant two way upload and download communication isn’t required. It has the same limitations as satellite TV in that rain fade and trees are a concern, but it does have the benefit of being able to be used in the middle of nowhere when cellular communication is spotty (at best) and where Wi-Fi is non-existent.

System Components

An entertainment system is just that – a system. In addition to an antenna, dish or other source, you need to have a distribution system and viewing devices. An over-the-air antenna or cable TV feed will send their output via a RG6 coaxial cable. An OTA antenna needs a bit of help, so an amplifier will utilize 12 VDC power to send a signal up through the coax to the antenna to boost the signal. Cable TV does not need this, so the cable tv coax is typically connected to the antenna booster switch, which actually acts as a 2-way coax switch as well. When the button is pressed it will illuminate, indicating that the amplifier is sending its signal to the OTA antenna. When the button is released, the pilot light will go out and the amplifier will turn off. At the same time, it will switch the coax input from the antenna to the cable TV feed. The output from this switch then goes to a coax splitter that can send the output signal to up to four different TVs via their coaxial input jacks. The internal tuners on each TV will be used to select the channels.

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Satellite receivers or DVRs require a subscription to a satellite provider.

A satellite dish also uses coax to deliver its signal but it’s not the same frequency as the RF signal sent by the antenna or cable TV. The dish outputs a high band signal that cannot be read by any TV. Instead, it must go directly to a satellite receiver or DVR, which is nothing more than a receiver with recording capability. The receiver will then handle the tuning and selection of channels which will then be sent out via HDMI cabling to an HDMI distribution amplifier, which can then send that information to an HDMI input on any of up to four TVs.

Local content, such as output from a Blu-ray player or laptop computer with an HDMI jack, can also be sent to an HDMI input jack on a TV. Most modern TVs have multiple HDMI jacks and can handle multiple feeds so that DVDs and satellite receivers can be connected at the same time. But most entertainment systems utilize a distribution center that allows switching from all of these inputs via a remote control and sends the output on a single HDMI cable to each TV via a 1×4 HDMI distribution amp. This also connects to a surround sound system or sound bar so that every input gets the same high quality audio. However, there are cases where a second source may still be desired, such as in the bedroom where a second Blu-ray player or satellite receiver may be used.

National Indoor RV Centers blog Mark Quasius Entertainment Systems for Class A Class B and Class RVs and motorhomes

Dongles, like this Roku, connect to a TV’s HDMI input to allow easy access to streaming internet video via a remote control.

In the case of streaming, there is no antenna or dish to provide a hard-wired signal. Streaming content is delivered over the Internet and sent throughout the RV via a Wi-Fi signal. If you want to watch this content on your laptop or iPad, you just access your web browser or smartphone app and log into whatever service you are registered with. If you want to view this content on your TV, it’s a different matter.

Some smart TVs have built-in apps that can log onto certain streaming services, but not every TV has that ability and the service you want might not be available on that TV. Instead, you’ll have to buy a wireless interface device that connects to an HDMI input port on your TV. These devices range from boxes with cables that extend to the TV to dongles that plug directly into an available HDMI port on the TV. These devices vary and include brands such as Roku, Amazon’s Firestick, Fire TV, Apple TV, Xbox and others.

Not every streaming source will work with every device, so you’ll need to match the device with the streaming services that you want to watch. Note that the average household utilizes three streaming services, so plan ahead before you buy. If you install the dongle on your HDMI distribution center, you’ll probably only need one device. But if you want to watch another feed, such as a bedroom TV that isn’t playing the same channel as the main feed, you’ll need a second device for that TV. Most aren’t that expensive and can be less than $50 while some, like the Apple TV, can cost quite a bit more.


Now that you have content available, what do you want to watch? Each service offers their unique selection of programming. Many networks are moving their main programming to streaming networks. So if you want to watch certain shows that used to be on free OTA broadcast TV, you may now find that you’ll have to move to a paid subscription for their streaming services. NBC created their Peacock channel, Disney has Disney Plus, Discovery channel has Discovery Plus and on and on. Most of them offer mostly proprietary programing, so you’ll have to decide whether or not they are worth it to you. Netflix is known for its collection of movies. Hulu, YouTube TV, Sling, Fubo TV and others offer various plans. Some providers, such as Tubi, Pluto and Freecast offer free streaming. 

Basic pay plans include advertising, but most offer extra cost upgrades that can eliminate ads and offer a greater selection of channels. Many offer live TV as well. Some, like Hulu basic, offer certain live network channels but to view those shows you’ll have to wait until the next day and stream them from their library. If you have a live TV option, you can watch them live in real-time, which is particularly helpful for sports. Or you can use their DVR service to record to your PC or their cloud-based service. 

It’s also important to notice that not every service that offers live network channels – such as ABC, NBC, CBS or Fox – will offer all of them. In many cases, one will be missing. The important thing to remember is to research the content providers first to see what you want to watch and what you can live without. Chances are you aren’t going to get it all and will have to give up something. This is one reason why most content consumers have more than one streaming source.

National Indoor RV Centers blog Mark Quasius Entertainment Systems for Class A Class B and Class RVs and motorhomes

TVs mounted on a power lift mechanism, liker in the Newmar London aire, are a popular feature in newer motorhomes.

Final Choices

Once you’ve found the provider or providers of your choice, check to see which devices will work with your content. Not every device will handle every single content provider so, after you’ve chosen your content provider, be sure to compare before purchasing your device. Nobody likes multiple devices hanging out of the back of their TV. 

A number of coaches now feature large 50” LED Smart TVs that are mounted on power lifts so they can be raised up for viewing and lowered into the cabinet when you just want to look out the window. Devices such as Roku can be had in a block design with a  cable that extends to the TV’s HDMI port or through a direct HDMI plug-in dongle. The dongle may be a better choice with a TV on a lift because it rides with the TV and you won’t have to worry about cords getting tangled or unplugged. However, this depends on where the TV’s HDMI ports are located. You’ll have to ensure that it doesn’t stick out too far so that it gets knocked off when the TV is raised or lowered.

To ensure safe and proper functioning of these entertainment systems, be sure you’ve got a solid understanding of your RV’s batteries and baseline knowledge of RV electricity too.

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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’s Family RVing Magazine. Mark and his wife Leann travel in their 2016 Entegra Cornerstone.

DEF Head Issues? Everything RVers Should Know About DEF (Diesel Exhaust Fluid).

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 the addition of a Diesel Particulate Filter (DPF) to the exhaust system to reduce the level of soot in the exhaust.

The next big step was the Tier IV EPA 2010 emissions standards which took effect for the most part in model year 2011 motorhomes. These regulations were a significant step in reducing pollutants from diesel engines and required some major changes in the design of diesel engine emission systems. The prevalent method of achieving this was Cummins’ implementation of Selective Catalytic Reduction technology, commonly referred to as SCR. In addition to the Diesel Particulate Filter, SCR technology adds more complexity to the emissions system but significantly lowers emissions below the EPA 2007 specifications.

The SCR aftertreatment system resides above the muffler on the exhaust manifold side of the engine.
The SCR aftertreatment system sits above the muffler on the exhaust manifold side of the engine.

The SCR system adds a decomposition reactor where Diesel Exhaust Fluid (DEF) is injected into the exhaust stream where it forms ammonia vapor. The ammonia and nitrogen oxides in the exhaust flow together and pass into the SCR Catalyst, where they react to form nitrogen and water vapor and reduce emissions to near-zero levels. SCR is aftertreatment technology so it destroys these harmful emissions after combustion, which gives the engine manufacturer the ability to fine tune their engines to produce maximum power, efficiency and fuel economy. Other than clean exhaust, the biggest impact upon coach owners is the necessity of having to maintain a supply of  DEF in the coach’s storage tank .

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’s first begin with a better understanding of the components of this system and DEF itself.

Refilling a DEF tank from a 2-1/2 gallon jug.
A shot of refilling a DEF tank from a 2-1/2 gallon jug.

What Is DEF?

Diesel Exhaust Fluid, or DEF, is a product designed exclusively for use in diesel engines using SCR emissions technology. It’s basically a non-hazardous solution of 32.5% urea and 67.5% water. It’s clear and colorless and has a slight smell of ammonia. DEF isn’t something you can make yourself and engine manufacturers specify that any DEF used should by certified by the American Petroleum Institute (API), the same people who rate engine oils and other petroleum products. The API has a Diesel Exhaust Fluid Certification Program that allows DEF producers to display the API certified label on their DEF packaging.

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

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

Instrument panels include a DEF level indicator
Instrument panels include a DEF level indicator as well, such as this common 4 LED bar graph display built into the fuel gauge.

Handling DEF

DEF isn’t overly difficult to handle but there are a few considerations to keep in mind. Bulk DEF is available at truck stops from dedicated DEF pumps located on the driver’s side fuel island, oftentimes right next to the diesel fuel pump and located behind a rubber flap to prevent freezing in cold weather. DEF is also available in 2.5 gallon containers at auto parts stores, gas stations and most large retailers, such as Wal-Mart. As long as the container bears the API Certification Label it will meet the ISO 22241 standards so paying more for certain name brands of DEF won’t give you a better quality of DEF. It’s only ammonia water and doesn’t contain additives like a sophisticated engine oil or high tech lubricant.

DEF can evaporate if stored at high temperatures for prolonged periods because it is 67.5% water but field tests have shown that there isn’t a significant risk of evaporation from DEF tanks as long as you keep your tank or container securely closed. DEF does have a shelf life of two years but this can be reduced if the DEF is exposed to direct sunlight or if the temperature remains above 86o F for sustained periods. DEF packaging does have an expiration date so keep that in mind if you plan on stocking up on DEF. Ideally your DEF should be stored in a location where temperatures do not drop below freezing or exceed 85 degrees and will be consumed within one year of purchase.

DEF Tank
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.

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

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

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.

Pump DEF nozzles
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.

DEF In Your Coach

Now that you know what DEF is let’s take a look at how it is implemented in your coach’s emissions system. It begins by storing the DEF into the typical 10 to 15 gallon polypropylene storage tank, which is required in order to prevent corrosion between the DEF and any metals. There are limits on the length of the hoses that connect the DEF tank to the engine’s emissions systems so you’ll find the tank located at the rear of the coach on a diesel pusher chassis or at the front if a front engine vehicle such as a Super C or Sprinter type chassis. Most side radiator chassis don’t have enough room to place the DEF tank on the driver’s side of the coach so the tanks will be located on the curbside. Unfortunately, pump DEF at truck stops is always on the driver’s side to accommodate the driver’s side DEF tanks on trucks so this doesn’t work well for an RV but in recent years the chassis manufacturers began to add additional driver’s side DEF fills to make it more convenient for a motorhome owner to use pump DEF when refueling. This does require moving the coach forward after pumping fuel so that the pump nozzle can reach the driver-side DEF filler at the rear but this a small inconvenience that is worthwhile because it allows you the ease of refilling your DEF tank and receiving the bulk pump price versus the higher cost of retail DEF jugs.

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

DEF Tank Cap
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.

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

DEF is a critical component and without it your emissions system will not work. EPA requires that the vehicle emissions system must be fully operational at all times so certain safeguards are put in place to ensure that you cannot continue to operate the vehicle without DEF. To ensure you know how just much DEF is in your tank, a DEF gauge will be located on the instrument panel. In most cases this is a series of four LED bars built within the diesel fuel gauge. Four green bars will be displayed whenever the DEF tank is fuel. Three green bars indicate ¾ full while two green bars indicated ½ full and one green bar indicates ¼ full. Once the level of DEF in the tank reaches 10% that last green bar will turn to amber. Typically the LCD Information Center on the instrument panel will display a “LOW DEF” warning in addition to displaying a warning icon on the panel. The vehicle will continue to operate normally but if you have allowed the tank to get this low this is the point where you really need to consider how soon you can add more DEF to the tank. If you continue on without adding, the amber LED bar will turn red when the DEF level in the tank reaches 5%. The Information Center will now display “ENGINE PERFORMANCE DERATE EMMINENT”. You now have very little time left to add DEF before your engine derates. Once the level drops to 3% the display changes to “ENGINE PERFORMANCE DERATE ACTIVATED” and your engine will be derated and there will be a 25% reduction on its torque output. You’ll still be able to limp off the road at reduced power but you’ll still be burning DEF as you do so and the next step is the final step.

DEF filter location
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.

Once the DEF tank gets down to 0% the red LED bar remains illuminated and the Information Center now displays “SPEED RESTRICTION ON. DEF REQUIRED”. Engine torque will now be limited to 60% and the vehicle speed will be limited to 5 MPH. That’s enough to pull off to the side of the road but you will need to fill the DEF tank to at least 10% in order to drive to a location where you can top off the tank. Carrying a 2.5 gallon jug or two of DEF as a safety precaution can be a wise choice, even if you normally refill with pump DEF at truck stops.

DEF systems aren’t high maintenance. If you store your coach over a longer periods of time or run the engine for very short and infrequent runs your DEF can get old and beyond its shelf life. In that case the best practice is to drain the DEF from the tank and replace it with fresh every year. There is a DEF filter located near the bottom of the DEF tank. This filter should be replaced every 200,000 miles or two years, whichever comes first. The filter is easily removed with a 1-1/16” 12-point socket and extension. If the cap wasn’t excessively tightened you may be able to remove the DEF filter cap with a channel-lock pliers without damaging the cap. The filter is at the base of the tank so you’ll be looking up at it. Just be sure that you are off to one side when you remove it because a bit of DEF will dribble out of the filter housing. The actual Cummins DEF filter is a small cartridge filter and comes with a small tool to help yank the filter out of the housing. This filter is sometimes forgotten by owners when servicing their chassis but a plugged or restricted filter can lead to a failed DEF pump, which is a more expensive repair, so do not neglect this filter.

Cummins DEF filter and tool
The Cummins DEF filter includes a small removal tool to aide in removing the filter from the housing.

DEF Sensor Issues

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’t 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’s exhaust system as well as the fact that hot engine coolant was constantly circulating through the DEF head.

When the sensor failed the engine would shut down, typically displaying one of the following fault codes showing abnormal update rates:

            SPN 3364 FMI 9 (Cummins Fault Code 3868) –DEF quality

            SPN 1761 FMI 9 (Cummins Fault Code 4677) – DEF tank level

            SPN 3031 FMI 9 (Cummins Fault Code 4572) – DEF tank temperature

These codes were designed to detect weak DEF, low DEF level or DEF that had been overheated in the tank. If the sensor chip fails any one of these fault codes may appear, even though there is nothing wrong with the DEF itself. But the faulty sensor will derate and eventually shut down your engine.

The Shaw sensors were revised over time but the newer revisions still had issues and as of generation 6 there were still continuing failures and many RVs were sidelined due to a lack of replacement sensors, mainly due to the electronic chip shortage affecting the automotive industry in general in addition to the time involved in developing a new chip revision. The EPA began working with Cummins to allow an industry-wide software solution to allow vehicles with failed sensors to operate temporarily until replacement parts are available. But the EPA and Cummins haven’t yet determined how soon this software update will be available so a few RV owners simply took the initiative and developed the software to create a DEF sensor simulator.

This simulator was a small electronic piece that is used to communicate with the ECM in place of the faulty DEF sensor. You simply unplug the 4 conductor harness from the DEF sensor and connect it to the simulator. The simulator is designed to provide normal readings to the engine’s ECM so that it can continue to operate without shutting down by transmitting normal readings to the engine’s ECM. The caveat to this simulator is that you no longer have any information as to the level of DEF in the tank so you needed to physically monitor the level of DEF in the tank. However, it allowed the owner to operate the vehicle and complete the trip rather than be sidelined. The system will still meter DEF to the SCR so the pollution abatement portion of your emissions system will still operate as designed.

The simulator is a DIY home build operation if you are handy with electronics. Check out https://defsim.myervin.com/def-sensor-simulator-quick-build for instructions on how to build this if you are interested. The software is offered free of charge. You just have to buy the components you need, download the free software to its chip and build it yourself. While it is illegal to modify a vehicle’s emissions system in an effort to defeat the DEF system, this simulator does not defeat the emissions operation so is therefore not illegal. It’s strictly a temporary way to operate your vehicle until it can be properly repaired whole still retaining full emissions capability.

Shaw’s latest generation 7 sensors began to arrive around May of 2021 and as of this writing there don’t seem to be failures with these sensors so it’s 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.

National Indoor RV Centers blogger Mark Quasius profile picture
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’s Family RVing Magazine. Mark and his wife Leann travel in their 2016 Entegra Cornerstone.