By Russ and Tiña De Maris
Earlier this month we wrote about the plight of flocks of RVers, sidelined or scared-to-death by their Cummins-equipped motorhomes. Imagine yourself far from your home base when your dash warning light alerts that there’s a problem with your diesel exhaust fluid (DEF) system. You have 100 miles to go to get help, or your engine will progressively “derate.” That means, you’ll reach a point where your maximum speed could be as low as five miles per hour. You know your engine maker: Is Cummins to blame?
How DEF works
A little history is in order. Diesel engines have a nasty habit of producing unhealthy byproducts in their exhaust stream. These emissions include nitrogen oxides and particle emissions which are linked to lung and heart problems, some of them chronic. In 2010 the Environmental Protection Agency (EPA) mandated reductions of both these exhaust products in medium- and heavy-duty vehicles, which included plenty of diesel-fired motorhomes.
The smog treatment system of choice utilizes DEF, which is a fluid that’s largely water with added urea. The beauty of a DEF pollution control system is that engine manufacturers can build a big, powerful engine and not have it stifled by air pollution control equipment, as the DEF system is an “after treatment” system. After your engine has roared out plenty of horsepower, the nitrogen oxides and particulates are blasted down the exhaust pipe, and sprayed with DEF. When DEF comes into contact with the nitrogen oxides, it converts them into harmless water and nitrogen. Seems like everyone should be happy: Motorhome drivers have engine power, and there’s less harmful pollution released in the atmosphere.
“DEF head” issues
In the last few months, however, scores of motorhomes, delivery trucks, and other DEF-using engines have been having issues. The pollution control devices that monitor the condition, use, and presence of DEF in systems, often equipped with Cummins engines, have been acting up. Monitoring systems are reporting a variety of “faults” with the DEF equipment. When that happens, the dreaded sequence of events begins. Get that DEF system fixed, or find yourself “de-rated,” maybe stuck in a repair facility. Is Cummins to blame?
Our initial contact with Cummins representatives regarding what many call “DEF heads,” or the DEF monitoring assembly, yielded this response: “This is not a Cummins part and my understanding is that it is procured by the chassis manufacturer, so you should probably ask them about this particular part.” True enough, chassis manufacturers like Spartan and Freightliner have their own sources of DEF monitoring assemblies, so to a degree Cummins is not to blame. We attempted contacting Spartan for comment, but the company never bothered to respond.
But there’s more here than just a monitoring assembly. A Nexus Ghost owner, who asked to not have his name used, approached us. He and his family were headed out on vacation in their motorhome, and a few hundred miles from home got the dreaded DEF sensor failure light on their dashboard. They ended up parked in an International dealer’s parking lot. “Sorry, but we don’t have that part available, and we’re not sure when we can get it.” The family had to make their own way home, and the motorhome languished on International’s back lot.
The real cause of the problem
Not satisfied to sit on his hands, this RVer posted his experience on an internet forum. In a flash, other Nexus owners responded that they, too, had been sidelined with DEF sensor problems. Not all were stranded – some had made it safely to their home base. But all had one thing in common: None of them could get the needed repair parts, and most got only vague answers as to when they might get them.
What’s the problem? It seems that many chassis builders were concerned that since DEF is largely water, when ambient temperatures go down, the danger of the DEF freezing rises. If the DEF freezes it may degrade, and potentially we could imagine expansion of liquid in a reservoir might cause physical damage. To avoid that issue, these DEF systems are fitted with a valve that allows hot water to be pumped through the system to keep the DEF from freezing. Sad to say, these valves are prone to failure. In the “fail” mode they are stuck open, allowing hot water through the system regardless of ambient temperature. How does that lead to a DEF sensor failure?
The heart of the DEF sensor system is a silicon microchip. Microchips are particularly sensitive to high temperatures. That’s why when you fire up your computer, you’ll hear a fan or two running – cooling those persnickety microchips. In the height of an engineering “Duh!” you’ll likely find your DEF sensor chips nestled right next to one of those hot water lines. Too much heat, and the chips give up the ghost. For our Nexus Ghost owner, chip failure meant a quick stop, waiting for a replacement.
The chips are down
Is Cummins to blame? Not directly, but in the end they might be the folks with the ability to make a fix. Point the finger at COVID-19, but you’ve heard the cry of complaint from auto manufacturers to appliance makers: We can’t get the chips! This is the same problem for the scores of unhappy motorhome owners. There is a genuine shortage of microchips, and the end of the shortage is not in sight. If you can’t get the chip, then your chips are down.
Cummins doesn’t build the sensors. Cummins doesn’t install the sensors. How is Cummins to blame? Or how can they help? We go back in history. When the EPA trotted out its rule that led to the manufacture of oceans of DEF, someone recognized a fly in the ointment. Imagine you’re on the golf course and have a heart attack. Somebody calls 9-1-1, and the paramedics jump in their diesel-fired ambulance to come pick you up. Oh, dear! That dreaded DEF system failure light comes on and your ambulance engine is de-rated. Would you get to the hospital in time at five miles per hour? Or if your house were burning, how long would it take fire engines to arrive at the same speed?
Cummins’ “solution” for emergency vehicles
Cummins was concerned that emergency responders could not be hampered by a DEF issue, or other emissions control issues. The EPA issued a “Direct Final Rule” that provided relief to emergency vehicles. Essentially, the rule said emergency vehicles could not be slowed down, nor have their torque reduced, simply because of one of these issues. Cummins’ response, in their own words, was that they “developed a new engine software specific to fire and emergency vehicle calibrations … This new calibration eliminates all emissions related vehicle speed or engine power (torque) derates. This includes derates associated with low level Diesel Exhaust Fluid (DEF), incorrect and SCR faults that some customers may experience ….”
Cummins isn’t building fire trucks and ambulances leaving out essential pollution control equipment. They’re simply programming their monitoring systems so that in the event that something goes buggy with the sensor (or even if someone failed to fill up the DEF reservoir), the engine will continue operating at full speed. Warning lights still indicate the system has a problem.
Your motorhome isn’t a fire truck. If it’s sidelined with a DEF sensor issue, is Cummins to blame? No. But Cummins, who is the holder of the proprietary rights to the DEF monitoring control software programming, might be able to help. Our Nexus motorhome owner, who works in the tech industry, thought perhaps they could. Why not have Cummins do a “software patch” that would do the same thing for motorhomes that it does for emergency vehicles?
What industry and government say
Our source approached both Cummins and the EPA. He tells us that high-level officials in the EPA admit they are aware there is a serious problem for RV users who are being sidelined by DEF sensor fault issues. He also told our source that as far as he could see, the EPA would be happy to consider issuing a temporary waiver that would allow industry to issue such a software fix – long enough for the microchip industry to catch up and allow a more permanent and less-polluting solution. But, he said, Cummins would have to petition the EPA to start the ball rolling.
Our Nexus friend reached out to Cummins, eventually reaching Tony Satterthwaite, Cummins’ Vice Chairman. He explained his own problem about his sidelined motorhome. He brought up the suggestion of Cummins asking the EPA for the waiver. Something that could possibly get these stranded RVers back home, or out of their yards. To his credit, Satterthwaite assigned a Cummins engineer to the case. The engineer’s “workaround” investigated using a different DEF sensor. Not the specified sensor, but one that might “make do.” Sad to say, the one that was located was a bit too tall to fit his motorhome. But a sharp-eyed mechanic at the dealership recalled they had a DEF tank and sensor. It had been taken out of another piece of equipment. Lo and behold, it was the exact DEF head he needed. He now has his motorhome back home after weeks of waiting.
Cummins’ answer to RVers
But what about the suggested waiver request? After a great deal of back-and-forth, Cummins’ Satterthwaite wrote back: “During our communications, you suggested that Cummins should seek a temporary waiver from the EPA to allow for the deactivation of engine de-rate protection for the DEF quality level sensor, given the supply constraints affecting the industry. We appreciate your suggestion, and we will continue working to ensure that our customers have timely access to parts like the DEF quality level sensor.” In corporate-speak, “NO.” Is Cummins to blame if your motorhome is sidelined? We’ll let you draw your own conclusions.
Let’s be clear: The EPA won’t necessarily grant the waiver that could put sidelined motorhomes back on the road. They might – they might not. But to its credit, the agency is evidently at least open to the suggestion. The ball is decidedly in Cummins’ court.
You can share your thoughts with Cummins management
Would you like to share your thoughts with Cummins management? Cummins’ Director of External Communications is a gentleman named Jon Mills. He’s assured us that if you direct your messages to him, he will “ensure that the leaders are made aware as appropriate.” You can e-mail him directly at firstname.lastname@example.org.
That this problem isn’t something that will go away soon is witnessed to by the plaintive email we received this past Friday afternoon. It’s from one of our readers, Bill N. He writes, “We had the dreaded three codes signifying the DEF head failed while starting the RV one morning. We have 18,000 miles on our 2018 Entegra Anthem, and are stuck 850 miles from home.” It’s too far for Bill to walk home. Maybe Cummins could buy him a bus ticket.
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Revision notes: 07/28/21 2130 PDT, revises Cummins’ contact information, per their request.