RVers stranded with bad DEF sensors

taylorbob1

Senior Member
Joined
Jun 25, 2011
Posts
2,321
Location
Fallbrook, CA
For those of you with DEF issues, an article published today:

https://www.rvtravel.com/bad-def-sensors-facts-human-toll/

RVers stranded with bad DEF sensors. What does this mean? Are you affected?

August 21, 2021
human toll
By Russ and Tiña De Maris
We’ve written several times about DEF (diesel exhaust fluid) sensors that have left RVers and other users stranded. We’ve seen there’s still a bit of confusion as to just what this all means, and what can be done. We thought we’d recap and simplify the situation. And we also wanted to share with you real stories, from real RVers, to illustrate the human toll of DEF sensors gone bad.

First the facts

What’s the background?

Most current USA-produced diesel engines are equipped with federal government-required devices that reduce nitrogen oxide tailpipe emissions.

So what does that have to do with anything?

A major way these emissions are controlled is by injecting DEF into exhaust gases. The DEF helps convert nitrogen oxide, an air pollutant, into nitrogen and oxygen. Both of these elements are found in the air we breathe and, in themselves, are harmless. A monitoring system ensures this process goes as planned.

How does the DEF monitor work?


kus-usa.com
To ensure the DEF in a vehicle system is effective, a monitoring system checks, among other things, its quality, quantity, and temperature. The complete monitoring system is made up of various parts and is commonly called a “DEF head.” If this system determines the DEF isn’t up to standard (or has run out), the DEF head sends a signal to the engine computer warning of the trouble.

The engine control computer, on receiving this signal, turns on a dash warning light. At this point, a sort of “clock” begins a countdown. For many users, after 100 miles or so the engine is “de-rated,” or slowed down to as low as five miles per hour. It’s a sure inducement to get the rig to a repair shop.

So why is de-rating a problem?

If your motorhome or truck is de-rated, you get nowhere fast. If your de-rate happens while traveling down a high-speed roadway, the chances of a rear-end collision from a faster rig are increased. Enter the human toll, not just from a real traffic accident, but the mental stress of worrying about it.

Why not just get the problem fixed and keep on going?

Like so many modern products, DEF heads contain silicon chip microprocessors. These are the culprits that are causing the problem – they’re failing. The chips are very specific in design, and require the appropriate replacements. But just as the auto industry is shutting down production lines due to the worldwide shortage of microchips, DEF head manufacturers are likewise plagued. Many RVers are being told replacement DEF heads could be months away. Meanwhile, their RVs sit immobile and useless. The human toll here is real.

If there aren’t microchips to fix the problem, can’t something else be done?

A temporary “fix” exists. While the EPA (Environmental Protection Agency) requires the DEF monitoring system, it recognizes some “essential” services can’t be stopped. For example, emergency vehicles simply can’t be de-rated, lest those rigs be put out of service. An allowance has been made to keep the DEF monitoring systems in place. They warn of bad DEF, but don’t de-rate the engines. If the EPA were to allow reprogramming of engine control computers in RVs in this same way, RVers could get on down the road.

Wouldn’t that cause air pollution?


amazon.com
It shouldn’t. The problem seems to be not bad DEF but, rather, an incorrect reporting of a DEF situation due to malfunctioning monitors. If the EPA were to allow this reprogramming, even if bad DEF were present, there’s a backup system to stop the problem. These diesel rigs are also equipped with nitrogen oxide sensors. If the DEF system were truly NOT working, and the rig began to produce harmful levels of pollutants, these other sensors would catch it. From there, the engine control computer is alerted, and warnings (and de-rates) would kick in. This would also stop any “enterprising” RVers from simply pouring water into their DEF tank, instead of purchasing and using legitimate DEF.

So why won’t the EPA allow the reprogramming?

The EPA says it’s working with “industry” to explore “all options.” A major player is Cummins, one of the leading engine manufacturers for the RV industry. While Cummins does NOT manufacture the DEF heads used in motorhomes, it does CONTROL the software that de-rates their engines. To that end, Cummins and the EPA must come to terms. This is the reason we’ve encouraged concerned readers to contact both the EPA and Cummins.

Wouldn’t this create an expensive problem for Cummins?

We’re told by industry tech folks that the actual rewriting of the computer code to do this would take minutes. From there, the new code could be transmitted to dealers via the Internet. Once the dealer has the new code, it’s only a matter of having a technician plug a tool into each affected RV and push a few buttons. It’s understandable that the dealer would need to charge some sort of fee for the work, but given the time involved, it shouldn’t be excessive. A bit of effort on the part of EPA, Cummins, and local dealers would go a long way to alleviating the human toll.

Some human experiences

We’ve heard from plenty of RVers who’ve been affected by the “DEF head debacle.” We’d like to share just a few of their experiences.

Robert R.’s trip cancelled
Robert R. recently bought a 2021 Tiffin Allegro bus. With just 4,000 miles on the odometer, his DEF gauge began “reading incorrectly.” Tiffin told the repair shop they’d be happy to send a new DEF head – but they couldn’t give any time frame as to when that might happen. Robert’s cross-country trip plans evaporated. “We can’t trust we can make it, so we cancelled,” says Robert. “Who wants to leave for a trip knowing you could be stranded at any moment?”

Stranded Phillip
Stranded at any moment? That worry materialized for Phillip G. in another “human toll” story. Phillip’s Dodge Ram pickup is his truck of choice for towing his fifth wheel. Out in Michigan, that dreaded dash light came on, and the countdown to de-rate began. Phillip dropped the fifth wheel in Mackinaw City and soloed the pickup into Cheboygan, 15 miles away. The dealer found a stored code, but on test driving it, everything appeared good.

Phillip hitched up, but less than 200 miles later, the dash light came back. This time, an Iron Mountain, Michigan, dealer said a new DEF pump was needed … if Phillip could wait three months for parts. That was a non-starter, so the dealer reset his computer, telling Phillip he could probably go 500 or 600 miles to search for a dealer with the part. He found one, in that 500-mile range, and started out. Sadly, that “500 or 600 miles” turned out to be only 200 miles. Another dealer reset the system again. Again, the count began, and on arrival at a third dealership, he was told that the system couldn’t be reset.

Phillip was stranded with 200 miles to go to get to the part he needed. He couldn’t find someone to tow his fiver to a campground, so he parked the rig at a park-and-ride lot. There the family took the cold stuff out of their refrigerator and spent the night in a hotel, as it was too hot to stay in the fifth wheel.

“The following morning I was able to sweet talk the Sauk City dealer into selling me the part without doing the install,” he reports. He was able to secure another vehicle and drove 380 miles round-trip to pick up the part and get it in the hands of the local dealer, who finally fixed his truck. He sums up his human toll this way: “Needless to say, this experience was very stressful and has made me a lot less comfortable about being on the road, especially far from towns.”

More than an intellectual exercise for Joe G.
The situation could be counted as an intellectual one, as in dollars and cents, like Joe G. experienced. His Ram pickup DEF head issue really cost him. The first dealer who got his part charged him $1,965 while the “list price” showed $1,450. “A wonderful profit opportunity for the Chrysler dealer!” says Joe. But that pump died just days later, and Joe got credit on it toward the next one. “The whole affair,” reports Joe, “cost only $2,907. This includes five days of car rental. What a deal! For less than $3,000 and one stressful week, we helped save the environment!”

But human toll costs more than just money, especially for Alexander G.
Alexander G. had a “dream vacation” in the works. But just weeks before departure, his RV rang up a “low DEF code” warning. He quickly learned there was a line of trucks at his dealership, all waiting for the same part. It seems the DEF head was on “national back order.” “I went through all the stages of grief,” Alexander reports. “Grief with the situation – denial, anger, bargaining, depression, and finally acceptance.” In addition to the grieving, Alexander lost money, but mourns even more the loss of what might have been. “My daughter is now a senior in high school and will be going to college next summer. This means that this opportunity might never happen again.”

* * *

We have no idea how many RVers are either stranded, or have been, while waiting for repair parts. We have plenty of other stories of RVers who haven’t been physically stranded, but their own human toll comes from the fear of even putting the transmission in DRIVE. They’re very much afraid that they’ll get stuck somewhere, far from home, when that dash warning light comes on.

This has to stop.
 
I was following your misfortune.
It’s an obvious issue right now for all diesels.

Just bringing it to others attention if they’re interested to know what all the fuss is about.
 
Knocking on wood here...... my F-550 has not had any issues and on top of that it sips DEF. I'm on the start of a 5500 mile trip so I am hoping I have no issues with it and I am looking forward to seeing if I can get through the entire trip on about 7 gallons of DEF.
 
110,000 miles with our Cummins ISB6.7L and few 'DEF' issues... 2014 Thor Palazzo

I remember one time early on when the DEF light came on, yet when I filled the tank, thinkg that it was the problem, the light would still not go off. Under warranty I took it to Cummins in Indiana, where they replaced a sensor.

A year or so later, the same condition occurred, but after I filled the tank it took me a while to get to any service center. The light eventually DID go off, though, so no service was needed. I read later that the system needs several times of ignition cranking before the sensor/system resolves the light condition.

Afterwards, and probably for the last 75,000 miles, whether the DEF light comes on or not, I don't pay attention to it anymore. It's always resolved itself, after several stops/cranks some time later. I've also never had any 'derate'.

Now, if the manufacturers could design an effective and CONVENIENT place to mount the DEF tank where the owner has SIMPLE access to filling it, I'll be happy.
 
A lot of the problems the S2rv chassis have is the def heater/cooling lines are not hooked up correctly. When the two hoses are run through the frame to the def head theres a blind spot where the hoses goes through. Whats happening is the lines get crossed and get hooked up to the wrong fittings. This causes the def heads to get to hot and fail

Freightliner put out a service bulletin to check the hoses when replacing the bad def heads. Supposedly Freightliner is now marking the hoses so they can be identified properly when coming out of the blind spot


Jerry
 
I have a dumb question regarding this DEF Head sensor problem.

The bulk of my awareness of the DEF Head problem I have gained from articles about RVers having this problem. I've followed it on this forum, but I've also seen it addressed in other RV magazines and newsletters. I don't have a diesel RV; however, if I had buying my 2015 Vegas all over again, I'd probably have bought a Class C on Sprinter chassis.

Two years ago I did a self-move from Tampa to a small town just outside Lancaster PA. I rented a large Penske diesel moving truck and it had a DEF system on it. So I'm assuming all rental moving trucks with diesel all are DEF equipped. In addition there is a plethora of Sprinter diesel delivery trucks on the highway. And again I assume they are all DEF equipped. Then there are a host of tradesmen trucks (plumbers, carpenters, HVAC, handymen, etc) driving Sprinter diesels all with DEF systems as well.

So my question is -- why is it that most of the articles addressing the DEF Head issue seems to be about RVers? Why are the RVers affected seemingly the most vocal majority?

I know to have an RV and experience this problem is a tremendous inconvenience and then to get towed and a get new DEF head installed can be an expensive situation -- but to be a tradesman and have your truck with all its tools and materials side-lined because of DEF Head Sensors is a HUGE loss of income. Why does there not appear to be much complaining from these other people effected?
 
Last edited:
A lot of the problems the S2rv chassis have is the def heater/cooling lines are not hooked up correctly. When the two hoses are run through the frame to the def head theres a blind spot where the hoses goes through. Whats happening is the lines get crossed and get hooked up to the wrong fittings. This causes the def heads to get to hot and fail

Freightliner put out a service bulletin to check the hoses when replacing the bad def heads. Supposedly Freightliner is now marking the hoses so they can be identified properly when coming out of the blind spot


Jerry

Only on 2018.5 and some 2019. My 2020 lines are correct and I have had multiple DEF issues. A recall was sent to affected unit owners.
 
I have a dumb question regarding this DEF Head sensor problem.

The bulk of my awareness of the DEF Head problem I have gained from articles about RVers having this problem. I've followed it on this forum, but I've also seen it addressed in other RV magazines and newsletters. I don't have a diesel RV; however, if I had buying my 2015 Vegas all over again, I'd probably have bought a Class C on Sprinter chassis.

Two years ago I did a self-move from Tampa to a small town just outside Lancaster PA. I rented a large Penske diesel moving truck and it had a DEF system on it. So I'm assuming all rental moving trucks with diesel all are DEF equipped. In addition there is a plethora of Sprinter diesel delivery trucks on the highway. And again I assume they are all DEF equipped. Then there are a host of tradesmen trucks (plumbers, carpenters, HVAC, handymen, etc) driving Sprinter diesels all with DEF systems as well.

So my question is -- why is it that most of the articles addressing the DEF Head issue seems to be about RVers? Why are the RVers affected seemingly the most vocal majority?

I know to have an RV and experience this problem is a tremendous inconvenience and then to get towed and a get new DEF head installed can be an expensive situation -- but to be a tradesman and have your truck with all its tools and materials side-lined because of DEF Head Sensors is a HUGE loss of income. Why does there not appear to be much complaining from these other people effected?

During one of my DEF breakdowns I talked to a trucker that has 22k in DEF repairs this year alone. His rig is no longer under warranty. Folks are screaming and there are quite a few articles in the trucking and logistics magazines discussing DEF issues.
 
My question are these DEF head failures a Cummins on certain chassis, or fleet wide. IAW what about the F550 diesel super C, Sprinter diesel, or Ram, GM, Ford pickups? Granted I haven't read all the articles, but everything I've see have been the Cummins on DP and some super C.
 
During one of my DEF breakdowns I talked to a trucker that has 22k in DEF repairs this year alone. His rig is no longer under warranty. Folks are screaming and there are quite a few articles in the trucking and logistics magazines discussing DEF issues.
Could it be that the RV builders relocate the DEF tank? I really have no idea. We only have 8,000 miles on our coach but zero issues.
 
Could it be that the RV builders relocate the DEF tank? I really have no idea. We only have 8,000 miles on our coach but zero issues.

No, don’t blame this on the RV builders. This is chassis manufacturers and the US Government. EPA mandates the derate if something is wrong.
 
No, don’t blame this on the RV builders. This is chassis manufacturers and the US Government. EPA mandates the derate if something is wrong.
Absolutely a proven fact

If you get on the the truck forums the numbers are truly bad

A lot of old Cat engines and pre DEF still on the road becof the costly issues

Also the reason for thousands of Deletes

We all pay for the failures ultimately
 
The Tuscany has a Freightliner chassis with a Cummins diesel. Thankfully no DEF issues ever.
 
Great article with accurate details, this is what I do for a living and the def header consist of the level sensor, temp, sensor, and a quality sensor as def is 32.5 urea the quality sensor checks this, the temp sensor is used to turn on the def heaters in the tank uses engine coolant and the lines are electrically heated, we have trucks sitting for months waiting on new headers but they are redesigning these with better quality.
 
Great article with accurate details, this is what I do for a living and the def header consist of the level sensor, temp, sensor, and a quality sensor as def is 32.5 urea the quality sensor checks this, the temp sensor is used to turn on the def heaters in the tank uses engine coolant and the lines are electrically heated, we have trucks sitting for months waiting on new headers but they are redesigning these with better quality.

A big issue on the 2018.5 and 2019 Seneca with the S2RV chassis is the Def Heater hoses were installed backwards. Freightliner issued a recall on those units to correct the problem.
 
.....cut....

August 21, 2021
human toll
By Russ and Tiña De Maris
We’ve written several times about DEF (diesel exhaust fluid) sensors that have left RVers and other users stranded. We’ve seen there’s still a bit of confusion as to just what this all means, and what can be done. We thought we’d recap and simplify the situation. And we also wanted to share with you real stories, from real RVers, to illustrate the human toll of DEF sensors gone bad.

......cut....


This issue doesn’t affect me directly either way, but I will say the article seems biased when it comes to the “human toll”. If you believe diesel exhaust causes health issues, which is why these DEF systems are there in the first place, then suggesting that they should be allowed to be bypassed in any way is opening the door to abuse. There are two sides to “human toll” and they ignore the flip side. Personally, I don’t care as long as the reprogramming does not involve rolling coal or some other type of idiotic behavior.

Reports suggest some companies are electing to switch lighter vehicle purchases from diesel to gasoline even though fuel costs are higher. A few are going to propane or natural gas. To Ed’s point, down time and repair costs can often offset fuel savings, so why bother complaining when you can do something about it?
 

Try RV LIFE Pro Free for 7 Days

  • New Ad-Free experience on this RV LIFE Community.
  • Plan the best RV Safe travel with RV LIFE Trip Wizard.
  • Navigate with our RV Safe GPS mobile app.
  • and much more...
Try RV LIFE Pro Today
Back
Top