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?
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?
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
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 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.”
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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.