Tuesday, November 28, 2023


Still stuck with DEF sensor issues? Email Cummins and the EPA

By Russ and Tiña De Maris
Last month we started out on a journey to try and help RVers who’ve been hit with shutdowns or fears of shutdowns with Cummins-equipped rigs. As we mentioned, for an untold number of motorhomers and pickup drivers, the diesel exhaust fluid (DEF) monitoring system issues have them sidelined with engines that refuse to allow them to drive over five miles per hour. No, Cummins isn’t responsible for manufacturing the DEF monitoring systems, but they do have control over the software that de-rates their engines when the DEF system fails. We’ve been trying to work with both Cummins and the U.S. Environmental Protection Agency for help, and we’re getting nowhere. It’s time to email Cummins and the EPA.

Eating some crow

Jon Mills. cummins.com.

It’s also time for us to eat a little crow. At the end of July we posted an article that suggested this same approach. In it, we published the names of top Cummins executives and their email addresses. Apparently that struck a nerve: Within days Cummins begged us to pull those names and addresses. They promised they’d help. They said if we’d publish a single contact person for their outfit, he’d see to it that your concerns would be forwarded “appropriately.” Some readers complained they’d sent an email and never got a response. We asked Cummins’ Jon Mills, the contact man, about this. He emailed us telling us about you: “I am sure there are some I have missed.” He promised to reach out to all.

That’s all very well and good. But when asked about a potential short-term solution to the problem, we got the same response back this week that we did in July. The solution? Since the EPA recognizes that emergency vehicles like fire trucks and ambulances must not be throttled back because of a DEF monitoring system malfunction, they allow industry to program that same monitoring system software to warn – but not de-rate an engine – if the DEF system reports a problem. Why not allow Cummins engines to be reprogrammed in the same way for RVs? Once the shortage of microchips that’s responsible for so many RVers being sidelined is resolved, fix the monitors, and go back to the old programming.

Talk is cheap

Insiders at the EPA said it was possible, and they’d be willing to talk to industry about it. And apparently they have been talking. Here’s the latest statement from Cummins: “We are continuing to work with our OEM partners to address the industry-wide DEF sensor challenges being faced by customers, as well as exploring other ways to overcome this challenge. Specifically, we are actively engaging with the regulators to evaluate potential solutions amid the global microprocessor shortage that is inhibiting the ability of our industry partners to overcome this issue quickly. We remain committed to doing all that we can to alleviate the impact this issue is having on our customers.”

Well, excuse us, but talk is indeed cheap. We reached out to the EPA for its take on the matter. A couple of weeks ago, insider information suggested the EPA was genuinely concerned about your plight. But now, we’re stonewalled. The EPA hasn’t bothered to respond to our inquiries, other than to ask for extensions to respond.

Enough is enough

Enough is enough. It seems we erred when we tried to “play ball” with Cummins and pull their executive contact information. We’re now restoring it. It’s time to email Cummins and the EPA. Here’s that list of Cummins executives, and a little background information on them.

Chief Executive Officer: Tom Linebarger. According to Securities and Exchange Commission (SEC) filings, this well-fed executive cashes in a $17,291,581check annually. That’s what? Over $47,000 every day, 7 days a week. Send him your fan mail at tom.linebarger@cummins.com .

Vice Chairman: Tony Satterhwaite. Satterhwaite takes home $4,607,396 annually (2020 figures). His email is: tony.satterthwaite@cummins.com .

Cummins’ Chief Financial Officer is Mark Smith. Mark’s annual paycheck (in 2020) was $4,000,096. Email him at mark.smith@cummins.com .

Finally, there’s President and Chief Operating Officer, Jennifer Rumsey. She’s new to the company, so we don’t have an SEC filing to learn about how much she’s taking home. You can email her at Jennifer.rumsey@cummins.com .

So, think about it. If these four people all jumped on the private company jet (yes, the SEC says that’s one of the “perks” they have in their packages) and flew into the same town where your broken down motorhome is waiting a fix, what would it mean? While you’re sweating it out, they’re earning more than $71,000 that day. Could they spare you and the family bus fare to get home?

Write the EPA, too

Next on your mailing list? How about folks that matter at the EPA? Since they’re on your tax-supported paycheck, they probably don’t make anywhere near the amount that Cummins execs do, but they are on your dollar just the same. Here’s their contact information:

The top dog is Michael Regan, EPA’s administrator. He’s relatively new to the job as a political appointee, but certainly knows the public helped get him where he is. His email address is Regan.Michael@epa.gov .

And the man who likely has the most weight in getting something done with industry that will give RVers some relief is EPA’s director of diesel engine compliance. Dr. Allen Duncan has been with the agency for nearly six years, and certainly knows the inner workings of the bureaucracy well. You can reach him at duncan.allen@epa.gov .

All of these folks, both from Cummins and the EPA, know of the problem. Maybe what’s missing for some is the human side of the equation. Perhaps if they heard how you’ve been personally affected by this seemingly glacial speed “evaluation of potential solutions” it might touch them. It seems apparent the solutions are there – it’s just getting enough willpower to implement them. Yes, by all means, email Cummins and the EPA.

And one more man who may not know your problems – yet!

But there’s one more person who we’ve not touched on before. On the Cummins board of directors is someone who knows more than just profit margins. He also knows the science because he, himself, is a well-schooled mechanical engineer. Dr. Robert J. Bernhard is a faculty member of the University of Notre Dame. He has extensive experience and “knows his nuts and bolts.” We’re not sure if Dr. Bernhard has been briefed by Cummins execs about this problem, but we’ve sent him an email on the matter. Since it was late in the publishing cycle, we have not yet heard back from him.

As a board member, Dr. Bernhard has company interests at heart. But at the same time, we have a hope that he also has an ear to what may be touching customers. Our advice: Reach out to Dr. Bernhard, let him know your story, ask for his help. His email address is rbernhar@nd.edu .

We’re hopeful that a deluge of concern from Cummins customers, and U.S. taxpayers, can somehow put the human face on this mechanical issue. We’ll keep you posted as to what we hear on our end.

We invite your comments below.


donateArticles like this do not write themselves. What other RV publication is committed to bringing you important stories like this? Please support us with a voluntary subscription so we can continue to bring you quality information and not just fluff from influencers and PR copywriters who have never even stepped into an RV!

Photo credits: Cummins executives, cummins.com. Allen Duncan, EPA from rocketreach.com. Dr. Robert Bernhard, nd.edu. Click to enlarge any. 


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Ninja (@guest_152706)
2 years ago

If you are waiting for a sensor, check out this for an option… They offer a sensor simulator. k1technical.com

Jim Brownfield (@guest_144157)
2 years ago

I work for a motorcoach company in the St. Louis area. We have been in talks with the EPA over SCR de-rates. Our contact person is kopin.amy@epa.gov. She has been helpful, and taking public comments over the de-rate issue, caused by SCR, and DEF, etc. codes. Please everyone send her an email too. We have a sympathetic ear with her. Unfortunately, the timeline for any change may be as far as two years off.

David Hobs (@guest_138870)
2 years ago

Before I mail my letter I’d like to verify firetrucks and other safety vehicles don’t derate.

Keith B (@guest_138891)
2 years ago
Reply to  David Hobs

Here was my reply to “Cummins Guy” a couple of days ago. This was a public release from Cummins. If you really want to get into it you can find lots of links to EPA writings on the subject using the search engine of your choice.

12Down (@guest_139383)
2 years ago
Reply to  Keith B


Rich (@guest_139473)
2 years ago
Reply to  David Hobs

This is correct. A here’s some info from Cummins – it’s a simple firmware update:

Craig (@guest_138805)
2 years ago

I hate having to use DEF. My 2016 Ram has 84,000 miles. Our only DEF issue was high consumption of DEF when the truck was new. A software update from the dealer solved it. Other than that, no issues. However, I do not think that 250 miles (on my Ram if I’m not mistaken) from an error until a derate is unacceptable. The mileage limit between the warning of a failure and a derate should be enough to get the vehicle back home, especially a motorhome, to where the owner can adequately take care of it and not be gouged by a roadside emergency mechanic. I would say 4 or 5 thousand miles or maybe implement a timeframe of 90 days. Then if you get to that point, go ahead and derate it because you were dumb enough to ignore an adequate warning.

Donald N Wright (@guest_138729)
2 years ago

Did you consider adding consumer Reports to your list ? They seem to have some clout at times. Maybe the folks at “Sixty Minutes” could mention this in their program.

John Morenz (@guest_138469)
2 years ago

Emailed everyone!

Steve Marsha Kraft (@guest_138466)
2 years ago

Received an auto response from Jennifer Rumsey that she’s out of town. She referred me to michelle.andre@cummins.com
Not sure of her title.

Last edited 2 years ago by Steve Marsha Kraft
Steve (@guest_138443)
2 years ago

First , thank you Russ and Tina for being domestic terrorist by printing these names. Second Russ, do you even drive a diesel? Third, please provide data on “the number of motorhome and pick up drivers” who have been hit with a DEF problem. My best friend runs a Ram with a Cummins and in 150,000 miles he has never had an issue. I drive a power stroke and have had an issue with DEF but it never derated me to 5 MPH immediately. I had 50 miles before there was an issue or it just gave me a check engine light, And Not every DEF issue derates the vehicle. I may not like DEF but I want my grandkids to breathe clean air so we need to work with it. I also never buy “jugs” of DEF. Buy it at the diesel pump, it will always be fresher. My question is how FEW miles do many of these units get driven after sitting for months and the DEF is old and has started to crystallize. There are always horror stories, but what is the real percentage of issues?

paul smith (@guest_138448)
2 years ago
Reply to  Steve

In defense of Russ I offer the following response. The definition of a terrorist is “a person who uses violence or intimidation….. to achieve a political goal”. Timothy McVeigh was a domestic terrorist. The Unabomber was a domestic terrorist. I don’t think any reasonable person would call encouraging people to email someone violent or intimidating. The people named in the article are being paid to produce outcomes for consumers. I would more appropriately call this article “informative consumer advocacy”. If one derated, slow moving RV doesn’t get rear ended by a semi as a result of the article effecting change would you still call Russ a domestic terrorist? How about if it had your family in it? Finally, you might take a moment to read the 1st amendment to the Constitution of the United States. Very informative.

Steve (@guest_138686)
2 years ago
Reply to  paul smith

We can agree to disagree. “A person who uses intimidation”, What do you think printing peoples private info on a public forum is intended to do. The goal is simply to encourage people to send them complaints, etc. at their homes. If this doesn’t rise to the definition of intimidation, I don’t know what does.

As I said in my original post, Russ and Tina, Please provide some data. Further, I don’t drive a Cummins but when my power stroke had a fault with the DEF system, I got a warning that I would be debated in 50 miles. It did not go into a 5 MPH derate immediately. And if it did, I sure the hell would not be driving any distance at 5 mph. I would get off the road ASAP.

So as I like to say, In god we trust, all others bring data!

Keith B (@guest_138463)
2 years ago
Reply to  Steve

I’m struggling to understand exactly what your point is. Are you disputing that there is a real problem because you and your best friend haven’t had it happen to you? Is it that not every failure of any component in any SCR system is the same problem as the specific problem being complained about here? Is your proposed solution that everyone should just practice good DEF hygiene and everything will be fine even though where one buys DEF has no likely relation to this specific problem. Is it that until some specific number of people have suffered from the problem then it isn’t a problem? Also how is it that you get to decide what that number is? Wait, I just realized that it must be that the guy who wrote the article doesn’t drive a diesel. Now I understand.

Steve (@guest_138679)
2 years ago
Reply to  Keith B

My point is they supply NO statistics. Is this 1 in 10, 1 in 100, 1 in 20,000. No data. I have driven diesels for many years and miles as have many friends and no one has had this problem. Every vehicle has issues sooner or later. Part of my point is diesel pushers and daily driver trucks don’t get a lot of miles put on them (I.e. – the reason I had DEF issues – not the sensor) Diesels are designed to be driven and worked. Sitting for long periods allow sensors and injectors in the DEF system to dry out and DEF crystallizes when it drys and the liquid evaporates. This will cause issues. So maybe driver education would be in order. And YES, good DEF hygiene may be part of the answer. DEF does not last forever. I am not suggesting that we should not advocate for improvements, but let’s make sure we are covering all the bases.

Keith B (@guest_138801)
2 years ago
Reply to  Steve

Thanks for clarifying. Not to try to be argumentative because I don’t disagree with most of what you said. However we may be talking about different things. First, for EPA reg purposes cars & pickups are treated differently from Heavy Duty vehicles like Motorhomes, which are in the same regulatory category as large trucks. Second, coming up with a % is impossible because the manufacturers don’t disclose the number of vehicles. I can tell you that I know a total of 7 people who own DPs. 4 of them have had the failure. And last, we are talking ONLY about DEF sensor failures. This is a very specific failure and generates very specific codes completely different from injector or pump failure. This failure has no proven connection to DEF age or condition at all.

Kathryn Burnett (@guest_143534)
2 years ago
Reply to  Steve

I have 7 KW’S they are always on the road 7 day’s a week and I have one sitting now waiting on a sensor that has not came now in over a month, this is the worst thing the EPA has ever forced on the trucking industry. Hope you are happy.

Diane Mc (@guest_138779)
2 years ago
Reply to  Steve

Go to the IRV2 forum and search DEF. Lots of stories. It is happening to many people. And no, it doesn’t go to 5 mph immediately, but you have to get it serviced/fixed within a small window or it will do exactly that. New def sensors are few and far between due to the part shortages many industries are having. All people are asking for is a temporary solution that is available for emergency vehicles to be applied to everyone until parts become available. Not trying to kill the environment. Meanwhile RV’ers are stuck on the side of the road sometimes in the middle of nowhere having to get towed where their motorhome sits waiting for parts.

Micheal Whelan (@guest_138351)
2 years ago

After this many years of customers being left stranded and in sometimes dangerous circumstances now is the time to quit talking and start doing. We were left along the expressway on our new coaches first trip. Cost us two months of idle time on the coach plus the very real expense of car rental (toad not yet ready to tow) and towing charges over and above the 200 miles allowed. Add that to lost deposits, additional meals and missed chance to visit the family. The federal regulation caused more pollution and danger to citizens than it cured. Another ill conceived fed regulation.
In addition to the email links you provided I also emailed my representatives. They are always saying they want to help….. now we shall see.

Last edited 2 years ago by Micheal Whelan
Maurizio (@guest_138347)
2 years ago

Cummins is out alternative brands are in 🙂

Keith B (@guest_138277)
2 years ago

…And to all of you armchair experts who likely haven’t actually worked on an engine since Jimmy Carter was elected kindly spare us your uninformed opinion on how you think the emissions systems work. I can assure you that the technology is more closely related to your iPhone than it is to your push mower.

Keith B (@guest_138273)
2 years ago

The number of commenters who ignorantly fire off comments like “you just don’t know how DEF works” “Call Shaw, it’s their problem. Leave Cummins alone.” And my personal favorite, “you must have a lot of money to be able to buy a big Motorhome. Therefore you deserve whatever misfortune is visited on you.” is infuriating.
Look, the sensors fail. Nobody that I know of has figured out for certain why they fail. The EPA promulgated regulations requiring “operator inducements” without thinking thru what happens if there is nothing wrong with the DEF, but the monitoring system failed. Cummins built the engine in accordance with those regs.
The source of the anger is that Cummins and the EPA figured out long ago that mindlessly disabling a vehicle wasn’t always smart. We are angry because Cummins and the EPA could mitigate the problem with nearly zero effort but are refusing due to there own selfish interests. Where is all that PR ‘We care about our customers’ BS when it matters?…

Cummins guy (@guest_138271)
2 years ago

I work for Cummins. The fire trucks and emergency service vehicles do shut down for DEF issues. I don’t know were you got your information about fire trucks and emergency service vehicles but it is wrong.

Barney Flint (@guest_138275)
2 years ago
Reply to  Cummins guy

Prove you work for Cummins!

Keith B (@guest_138278)
2 years ago
Reply to  Cummins guy

How about this statement from Cummins?


Does Cummins know you work for them?

Goldie (@guest_138244)
2 years ago

Having the sensors fail can be operator error but I can tell you it was not that when ours failed. My DH tests every jug of DEF that goes into our tank, and the tank get tested before the coach gets moved. We use down to about half a tank before refilling with fresh, so the DEF is continuously refreshed. Shaw Industries is now on the 7th generation of DEF sensors. Our Gen 5 failed, we now have Gen 6 installed – and we know those are failing also with disgusting regularity. To my knowledge, Gen 7 has not yet experienced failures but the number of folks who have been able to get one are so few that it may still prove to be unreliable.

Shaw is not the only supplier of DEF sensors. We know of folks who have talked to people at Spartan and Cummins and have been told they will not seek an alternate supplier, even if only until Shaw gets a reliable, consistently available product. Email every person, every day and include your Congressman. This needs to stop before someone is killed.

Paul Smith (@guest_138261)
2 years ago
Reply to  Goldie

Having been derated that is my biggest fear. Some semi is going to rearend a derated RV. I dont think the people named in the article understand that.

Montgomery D. Bonner (@guest_138221)
2 years ago

It should be emphazied that, part of this issue is “chips made in China or counterfitted, which are substandard”, and the vendors of the equipment refuse to fix. Yes, the supply chain is past broken. This will not improve, until all americans realize, if you want the best, not necessarily the cheapest, but the best, build it here, and make sure all vendors are required to keep 90 days of inventory on hand to meet failures of this kind. Expensive yep, sure is, but so is a 500,000 dollar motorhime sitting in a lot waiting on parts. Or the big rig which is needed to move the exact same parts which are keeping him stuck. I won’t go into the fact, paying people to raise kids, and sit on butt instead of working is also part of problem. It does NOT in fact take a villiage to raise kids, ask my dead grandmother, she did it 5 times over without a villiage or free money from the government.

Bob M (@guest_138073)
2 years ago

Maybe another solution is to pass the DEF issue information to potential buyers of vehicles with Cummins engines. Not to buy the vehicle till Cummins resolves the problem

Jesse Crouse (@guest_138072)
2 years ago

Until somebody’s ox is getting gored they have NO incentive to do anything but collect their checks. KEEP UP THE GOOD WORK. Let their lives become as miserable as the de-rated diesel owners have become.

Thom R (@guest_138063)
2 years ago

We need email addys for Shaw and the RV builders. They need to feel some heat too!

R. Wold (@guest_138061)
2 years ago

It’s interesting to note that the EPA website includes a wonderfully meaningless blurb on Environmental Justice (whateverthehell that is) but absolutely nothing on the insuring the safety of their policies.

Here’s a couple more contacts for folks interested in sharing their thoughts and experiences with decision makers:

Senate and House RV Caucus contacts:

• Senate: Contact the office of the Senate RV Caucus Chair,
Senator Joni Ernst (R-IA).https://www.ernst.senate.gov/public/index.cfm/email-joni
• House: Contact the offices of the House RV Caucus co-chairs, Representatives Dina Titus (D-NV-1) https://titus.house.gov/contact/
Jackie Walorski (R-IN-2). https://walorski.house.gov/contact/email/

Crowman (@guest_138047)
2 years ago

I have a Ram 2500 with the 6.7 Cummins so I have years of experience with the DEF system. DEF fluid like it or not has a shelf life that can be as short as 2 months stored in a 100 degree environment even in an unopened container. I believe that most of these problems are the owners themselves filling or leaving the DEF fluid over the time they don’t use the motorhome and it going bad causing the problems. I’ve suggested this before to watch on youtube a mechanic that has 2 episodes on the DEF fluid and system that explains the how to not have the problems most of these people are having. On youtube search for
MotorCity Mechanic and search his videos for the DEF video’s. When you understand the system 99 percent of you won’t have the problems they’re complaining about. I have over 55.000 miles on mine without one problem because I learned the do and don’ts of the system. Good luck.

David Telenko (@guest_138092)
2 years ago
Reply to  Crowman

CROWMAN, so you say that the DEF user (me-them-us) are the problem! So how is one supposed to know that the jugs of DEF we just bought is fresh, I just bought some & didn’t see a date on them. How about if the DEF got stored @ over a 100 degree temperature, it doesn’t come with a history of storage! As far as having the DEF stay in its tank while not in use, on mine there is no drain valve on the tank. The Freightliner dealer that I went to gave me an ESTIMATE of $1500.00 to Remove the tank & drain it (turn it upside down) & reinstall it! I do understand you should use up the DEF but most DP don’t, most likely keep the DEF tank full! So with C-19, a lot of DP motor homes sat idle & still are in storage! Now we have 2 scares hanging over our heads!
I found this https://www.youtube.com/watch?v=JSEg3ATml_E

Timothy l Vanderploeg (@guest_138188)
2 years ago
Reply to  David Telenko

Everyone i buy at Walmart has a date right on it if you can read and write, I know if you were educated in the US in the last 20yrs that might be a issue, I myself graduated way back in 1991 so maybe things have changed. Just use your eyes and remember you can’t buy a bunch of DEF and store it.. If you don’t drive your rig much its probably better to run it down before storing then put fresh in before you start it up next season, just like getting stuck with old gas in in your boat but there’s no stabilizer for DEF so fresh is best.

RV Staff
2 years ago

No need to be rude, Timothy. Sometimes it takes me awhile to find a date stamp on something. You graduated “way back in 1991”? You’re just what my dad would call a “whippersnapper.” I graduated in 1964. Maybe us older folks were just taught to be more respectful. Have a good day. 🙂 –Diane

Crowman (@guest_138769)
2 years ago
Reply to  David Telenko

If you watched the video I referenced he told you all about your questions you asked. There’s more to cleaning out the DEF system than dumping it out. Watch the video.

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