Last year, untold numbers of diesel truck and motorhome owners were stranded when their rig’s DEF (diesel exhaust fluid) systems acted up. Some sat it out for weeks—even months—waiting for unavailable repair parts. Other RVers left their vehicles parked in their driveways because they feared their engine might act up, leaving them stuck beside the road.
The problems stemmed from faulty DEF sensor readings, which caused engine computers to “derate” or severely reduce operating speeds. At the heart of the matter are pollution control regulations from the Environmental Protection Agency. The agency got an earful about these problems, and now the EPA proposes new rules on engine derating. How might you be affected by these rules?
What’s all this about derating?
What’s behind derating? A little background will help explain. The EPA set new rules for diesel engines manufactured from 2010 onward. They set air pollution standards, and industry was obliged to figure out how to meet those standards. In the end, the industry’s answer was to use DEF, essentially a mixture of water and urea. Pump a controlled amount of DEF into the exhaust stream; there the DEF is converted to ammonia. The ammonia then breaks down nitrogen oxides, significantly reducing pollution.
With the DEF approach, the EPA was concerned that drivers would be reluctant to spend the money or time to keep putting good quality DEF into their vehicles. Perhaps they might just pour water in their DEF reservoirs. So the agency told manufacturers they had to install DEF monitoring systems. If somebody failed to use DEF or, say, watered it down to the point it wouldn’t do the job, they needed a wrist-slap. In EPA parlance, an “inducement” was required—something that would make using quality DEF more desirable than not.
The EPA proposed manufacturers “include a derate of the engine’s maximum available engine torque of a sufficient magnitude for the operator to notice decreased operation.” The agency suggested that “at least 25 percent” might be enough to notice. If DEF wasn’t refilled, then a “progression to further degradation” might be in order. The industry took the EPA’s “suggestions” to heart. That “progression of degradation” for many manufacturers meant failing to respond to warnings would leave a driver with a rig running no faster than 5 miles per hour.
More issues
What industry failed to account for, or at least interpret properly, was additional guidance. The EPA told the industry the idea would be that the “inducement” “should not create undue safety concerns, but should make sure vehicle operators are adding DEF when appropriate.” It’s hard to picture how a motorhome traveling a busy interstate highway, derated to 5 miles per hour, could be anywhere close to avoiding “safety concerns.”
Last year’s debacle of motorhome owners stranded beside roadsides brought up another point, also addressed in the EPA proposal. The vast majority of RVers stuck with derated engines had good quality DEF in their tanks. The problem was faulty DEF sensors, reporting nonexistent problems which triggered the over-enthusiastic derate responses. In most—if not all—cases, the pollution control systems were actually working. DEF was being pumped into the exhaust stream, and nitrogen oxides were being properly reduced. But the technical glitches sidelined RVers who had no control over the problem.
Changes for 2027
The EPA is now working on rules for heavy diesel vehicles that would go into effect in the 2027 model year. Among those rules, the EPA proposes changes to the engine derate issue. Instead of making suggestions, the agency will frame rules for the industry to follow. What’s the bottom line?
For “high-speed vehicles” like trucks and presumably motorhomes, if operators failed to keep the right quantity and quality of DEF in the tank, here’s what would happen. A dash warning system would tell the driver there was a problem with the DEF system, and a refill was needed. If the warning was ignored, then the vehicle speed would be reduced to no more than 65. After six hours of failing to respond, the speed would drop to 60. At the 12-hour mark, 55 would be the maximum speed. And if the driver took no action, then 50 miles per hour would be the top speed after 60 hours from the first warning.
But what about technical glitches, such as the ones that have caused RVers so much grief? Motoring along with a full tank of high-quality DEF, but derated, nonetheless? The EPA proposes that if the rig is still passing nitrogen oxide standards, as measured by the vehicle’s own sensors, then no derate would happen. The driver would still get a warning, but the engine computer should not kick in speed derates. For do-it-yourselfing RVers, the new rules would also allow them to use a generic scan tool to reset the onboard computer, once they’ve made the necessary repairs. That’s quite a difference. At present, you’d need the specialized service of a shop to get rid of those “check engine” lights related to DEF system problems.
But what about existing rigs?
Should the EPA’s proposals become a rule, all’s well and good for 2027-and-beyond rigs. But what about those who are laboring under DEF sensor problems today? Is there any light at the end of the tunnel? Writes the EPA in the March 28, 2022, Federal Register, it may “be appropriate to allow engine manufacturers to modify earlier year engines to align them with the new regulatory specifications.” The agency is quick to add, “We are not proposing to change the regulation to address this concern. We are seeking comment [from industry and the public] on whether and how manufacturers might use field-fix practices under EPA’s field-fix guidance to modify in-use engines.” They add this could include changing existing “5 mile-per-hour” derates to the 50 mile-per-hour over 60 hours proposal.
It would seem the ball will largely be in the engine manufacturers’ court on this. Will Cummins, et al., be willing to spend a few hours of programmers’ time to rewrite the engine computer control codes? If they were, then will they likewise provide the wherewithal to have that new code plugged into existing engines? Only time will tell. For those who worry their existing rig could be sidelined by false reporting equipment, there’s a solution. Check it out in this article, It’s out there – a DEF sensor workaround.
##RVT1052b
They should have done this 5 years ago, not 5 years from now.
I’m an ASE master certified technician in heavy truck and automotive. Everything I own is compression ignition. My lawnmower, trucks and my farm tractors. I have never purchased DEF and I absolutely never will. The unreliability alone makes it not worth it, not to mention the fuel economy and power losses. Fuel prices and “emission controls” are killing our economy faster than anything else.
Q. What has 152 legs and 12 teeth?
A. The commenters on RVTravel.com
I just counted mine. THIRTEEN, so there!
DEF is snake oil. If you don’t buy it your car engine stops working. The snake oil vendor says it’s “illegal” not to buy it. He uses the old “saving the planet” routine.
I just got an entire system delete for my 17′ Cummins 6.7. EGR delete, 4″ straight pipe, S&B Cold Air Intake, EFILive Race Tuner. Gained about 30-40 HP and comparable torque numbers. Also gained around 7-10 mpg. With diesel in my area roughly $5.60/gal. And 28 gallon tank, your talking minimum 200 more miles per fill up. The weight reduction alone from all the emissions junk would slightly improve fuel mileage.
I hope they take it away from you.
Think about it I catalttic converter decreases horsepower decreases horsepower and overtime worsens the problem by decreasing horsepower you’re also decreasing efficiency and if you’re decreasing efficiency you’re using more gas and if you’re using more gas you’re putting more pollutants in the air and if you’re putting more pollutants in the air then what’s the point of a Cadillac converter, so what it burns a 30% more Combustibles at The cost of efficiency which will make you pump more in the air
He’s just doing what the government told him to do which is to rebel.
Call Bryan up, and talk to him in tree hugger language, he’ll listen, I’m sure of it.
Aftermarket tuners and delete kits can still be bought but they say there for off road use same tuners and all same price just cut the catalytic converter open an clean it out and weld it back and delete the egr system no problems
I just did that to my 2017.
Note that some direct injection diesel engines use EGR to control exhaust temperature in addition to reducing NOx emissions. If you delete or block the EGR you have higher probability of cooking your turbo.
I have a 2015 6.7 and I use very little def fluid. I also installed a tuner to over ride the existing computer. Now I dont have any issues at all for anything. But I do recommend using blue def. Dont try to save a couple of dollars by using the cheap stuff. There is a reason its so cheap. But to replace the exhaust system is about 7000.00. I have friends who own dodge and chevy diesels, and they tend to use more def than I do. It helps to have a light pedal foot too.
Delete system if trucking industry would grow a pair pour their $$ in older models maybe they would have engine and truck manufacturers also in the fight
What is the EPA doing about the smoke pollution from the trucks starting on fire during regen??
Not just the truck fire I have read stories about brush fires also. The warning states to make sure of your location when doing a Regen. But, you don’t always have a choice in that.
The lie began with “good quality DEF” Will you please just stop with such baloney. The EPA is an agency out of control. They, under the unconstitutional and crazy Chevron Doctrine, somehow think they have legislative power, with abilities to regulate and penalize. THEY DON’T. We the people put up with their crazy non-sense. They need to be sued into oblivion and put them back to their original intent, to give advice to the congress. Only the congress has authority under the US Constitution to pass laws. The EPA, has no constitutional authority. You really should take the time to read it. IT’S NOT IN THEIR.
As you will find out in June, when Roe v. Wade is reversed. Why, BECAUSE THE CONSTITUTION DOESN’T SAY IT. It really is that simple.
You’re right. The Constitution doesn’t say anything about an agency protecting the health and well being of the population from known carcinogens.
Did Ben franklin drive his F-350 to Convention Hall in Philly?
Why of course not. Ford Motor company, began business on or about 1903, silly man.
Ben Franklin was credited with a major pollution event, when he invented the “Franklin Stove” Oh, the wood smoke pollution, such a travesty, all in the interest of keeping people warm. HOW DARE HE!
I’ve never met a carcinogen so they’re unknown to me. How many carcinogens have you met? What do they look like? How come you can see them and I can’t?
Go for you. It is we the people
Congress has the constitutional authority to delegate authority to whomever they please. And how did we go from DEF to Roe v Wade?……sheesh…..
Sorry WCC, the only power Congress can delegate is it’s “advice and consent” power for inferior Officers. Read the Constitution.
So funny.
Everybody complaining about the “Gov’t”.
The real problem here was the manufacturers could have set the engines to derate to any speed. The EPA wanted something to get a driver’s “attention”. The EPA did not tell them to set it at 5 mph.
So why did manufacturers set it to 5 mph?
Why do manufacturers not keep enough stock of replacement parts on hand? This isn’t just about DEF sensors.
I had an ’09 Silverado and a brake sensor went bad. It caused me to have no trailer brakes because the sensor worked with the factory brake controller. I had to wire in an aftermarket brake controller so I could tow.
GM had no, I mean no, nada, nothing, in the whole country for spare sensor. It was six months later the dealer called to say they now had the sensor, bring the truck in.
This was in 2016. No “pandemic excuse”.
I told the dealer forget it, I was getting rid of the truck and I bought a Ram dually.
Agreed. Who would possibly think that 5mph amounted to a 25% decrease? Duh!
The real problem is somebody threatening to steal your car if you don’t buy his snake oil.
Disagreement here: The over sensitive DEF system is likely not the answer. Today I have a $330,000 motorhome and two Mercedes Bluetec wagons that have not run on a public street for two months, and no one can identify the issue, no codes no messages No speeds over 45mph.
The plan here is to eliminate high quality diesel engines from our choice selection, by bankrupting the consumer.
Remember back when we decided on 10% of cars in California would be electric, GM and Honda stepped up and later Chrysler, Ford and GM Sued the California EPA? They won the state through in the towel. Soon after GM crushed all the electric cars. Had that not happened we would likely not have this issue today.
A suit by 2 million Americans would be a good start, not against the auto makers but the EPA. How about dropping EPA requirements on vehicles over 9 years old, well after the point most businesses and individuals trade in the previous examples. Or require a system that lasts for 300K miles under warranty like exhaust systems.
I feel we have gone backward 50 years here, as people are scrapping selling or replacing just the Emissions system after 5 years or 110,000 miles.
Diesel engines are not the problem, the fuel and the crap refineries are getting rid of via your tail pipe is the problem. And regardless of what has been said, Government is deeply in bed with big oil, and always has been.
Fuel options are poo pooed and outlawed in favor of the same old fuels with some magic science lowering NOX, big deal. The chemicals not being recorded are the scary part.
I love diesels, I have 6 of them and only one car with a Gas powered V8 running E86 for racing.
I hate to cow under, but I have purchased a pre-DPF truck to replace my current unit. Let me buy an electric car to “Offset my other vehicles, as I doubt a one ton truck will ever pull a 16,000 lb trailer from dawn to dusk.
The EPA is the problem not the manufacturer. The EPA needs to get out of the automobile business.
If they did the price of a new F350 would come back to earth! I bought a new F350 4×4 with a 7.3 turbo diesel in 1993 $17,000 the same truck today $65,000
Runs prewoke engine solves all these issues!
Why can’t they be like Mahindra? I have a 2018 tractor that doesn’t have to have def fluid in it. So if a tractor company can build a diesel engine that doesn’t have to have it why can’t your auto companies do the same thing?
If it’s under 75 hp you don’t need def in any diesel
Now under 25
Correct, it’s engines under 25HP. Why you ask, because the lunitic EPA made up a law, picking some random HP rating. Those clowns had no jurisdiction in doing so.
My 99 Cummins needs no def and over 500hp, and no emissions from factory. Gonna drive it forever.
DEF (urea) is required in practice to implement EURO6 emission limits. I would assume a tractor doesn’t need to pass those limits.
Some engine designs can pass EURO5 requirements without extra additives just fine. It’s just the stricter requirements of EURO6 that are next to impossible to implement without additives.
Y’all, just use ammonia and distilled water from any grocery store. Just get the concentrations right, but a water ppm tester to get the recipe right, and save hundreds of dollars
While electric cars make a lot of sense, you don’t think they will develop some kind of system that will disable your car if you make a social media post they don’t like? They literally developed tech that disabled your car if it thinks you’re doing something they don’t like.
They can do that for any gas or diesel powered vehicle as well. All of the big 2 US auto manufacturers and Fiat Chrysler can monitor your vehicles remotely, upload/download information and better than ten years ago, hackers could hack your car and apply brakes, shut it down or do pretty much whatever they’d like. The more automated tech options you have, the greater the amount of things that can be controlled. It doesn’t have to be an EV for that.
You got me so worked up, i just went out and opened my wifes hood, and cut as many wires as i could fjnd with a sawsall. That will teach em to try and monitor me.
Electric cars have batteries that will contaminate the earth for the rest of eternity hahaha how safe is that especially when those batteries only last ten years
The car will lock the doors so you can’t get out and then it will drive you to the nearest police station where they will be waiting for you with a microchip and a “vaccine”.
My 2020 GM pickup had DEF heater go out in March it was 4 degree’s for a few hours, DEF freezes around 12 Degrees, had to be hauled to Dealership at that time they were 8800 units behind currently only 6600 behind a Technical Service Bulletin 21-NA-007 was issued in January 2021 for trouble shooting problem. Was never notified, truck sits at dealership with no estimate of being repaired.
EPA should foot the bill for their mistakes
Have you ever seen how much smoke a cummins puts out when it Regens my 09 doesn’t have Def it uses diesel now that’s environmentally safe to see black smoke plummit
My 99 cummins needs nothing and no emissions what so ever from factory.
Today Transportation Economy in the US is still Diesel while in China and Europe (thanks to Putin) is more and more Electric and less fossil fuel… the future is young 🙂
You really need to stop saying such things that are nonsense. It’s embarrassing when stuff like this is said.
Are they using electric tanks and ships to kill people with or are they still using diesel?
Maybe I’m missing something.
The SCR Systems already had both Into Treatment and After Treatment NOX sensors, performing similar functions to the gas engine OX sensors. It should have been obvious that a check on the DEF Sensor could have been in place and determining if a fault was actually happening, or if it was merely indifference.
Are the EPA and the Manufactures just content ignoring the problems that they are causing for Truck and other Diesel engine users ?
Def will not matter if the diesel engines that transport our products across the world viaadministration. rail, roadway are transformed to electric per the Biden admin’s. genius proposal & regulatory edict.
Regarding GM, they have never recalled the 2011-2015 LML sensors nor the imploding CP4 fuel injector pump.
Accountability is gone due to the absence of responsibility. We settle for less.
Why do trains not have to use Def ever seen one them smoker’s rollin
You do know that trains use big gigantic Electric motors right powered by diesel engine it’s essentially electric vehicle powered by gas, also the American power grit would never be able to withstand everyone running on electricity for the motor vehicles, not unless everyone was running on solar and I don’t mean grid tie inverters, i’m talking about off grid systems with 18,000 watt running on 240 V 48 V batterie bank.
Seeing everything run on sensors that work on electricity,how come someone doesn’t invent a plug in sensor that reads correct all the time? Proper capacitance or resistance? Seems simple but I was never good in electronics. I’ve had my share of trouble on my 2011 chevy duramax (first year of def)
There’s a link in this article that describes such a device. A lot of people are having difficulty working them because of connector difference etc, but the wires can just be directly connected.
Humans do not have technology to make any sensor that doesn’t fail. And creating a device that measures amount of NOx in your exhaust pipe is double hard because there’s always some amount of soot that messes all surfaces over time.
I think the correct fix would be to introduce easy to replace standard sensor and you could then keep spare part in your car that can be plugged in place in case of sensor failure.