Why DEF is the trucking acronym that gets my blood boiling

DEF. I don’t think there is a more hated acronym in all of trucking. DOT even pales in comparison. Would you rather a CRA audit, or DEF issues?

“Alex, I’ll take CRA audits for $1,000 please.”

DEF, of course, stands for diesel exhaust fluid. Unfortunately, North American governments have been “DEF” to the problems it has created. Manufacturers, dealers, trucking companies large and small, and drivers have all been affected.

Those who know me know environmental concerns are high on my priority list. Emissions systems requiring DEF have largely eliminated black soot from our exhaust pipes. That’s great, but it has created many other environmental problems.

The one segment of the industry who are not negatively impacted by DEF are the fueling companies. I know they’ll jump up and down and scream about this, but look at what happens every winter. As soon as temperatures drop, off go the DEF pumps.

I lumped all of the fueling companies together, which isn’t really fair, because some of them actually have pumps that work fairly well in cold weather. Most notable is Petro Canada. The ones they use are in cabinets and tend to be reliable. At least as reliable as anything can be in our northern winters.

I spent some winters on the ice roads and you can produce diesel that stays fluid, but the seals and switches are still a problem. DEF is basically water with urea. Its freeze point is lower than water because of the urea, somewhere around -15 C. The amount that we use as we’re hauling freight is fairly minimal.

In the winter we can run a few days before we need to top up DEF, and even longer in the summer. Here’s where the problem comes in. We rock up to the DEF pump and guess what? The pump is disabled. Not broken. Not frozen. Disabled!

If you’re in desperate need of DEF you will be buying it in jugs. Single-use plastic jugs. Didn’t some places ban plastic straws because they end up choking aquatic species? I was at a major fueling station the other day when the temperature was 0 C. DEF will not freeze at that temp but, yup, the DEF pumps were disabled.

Want to know what happens when my DEF doesn’t pump as I’m pounding the pavement? I will be gently coasting along under limp mode. At highway speeds our governments have decreed that no matter the temperature DEF must remain operational.

This is why DEF is the most hated acronym in trucking. A sensor glitched briefly? Limp mode. The DEF line froze? Limp mode. All systems not 100%? Limp mode.

Diesel exhaust fluid or DEF sign posted in a truck stop, next to fuel pump
(Photo: iStock)

These issues took effect immediately when the DEF requirement came out a decade or so ago. It was horrible. Manufacturers were scrambling. Companies went bankrupt, unable to meet their deliveries. The last truck I owned had a 2013 DD15 under the hood. If a sensor could cost me around $1,000 (downtime, tow, sensor) for a glitch, I wasn’t interested in owning my own trucks anymore. I had been owning and running my own for years, including having my own authority for a few years. I started carrying sensors so I didn’t have to rely on a dealer.

There was no legal way to get around this issue. That prompted another business to crop up. Emission system deleters. This proved to popular anywhere it got cold outside. In other words, all of Canada and the northern states.

Can you blame drivers and companies for doing this? Go bankrupt or delete? If a snowplow or fire engine could get an exemption, why were we being held hostage?

In the meantime, the manufacturers were scrambling, trying to fix the issues. In the decade plus, they have done an admirable job. I rarely have an issue these days with my DEF system with one main caveat. I am very strict about idle time which is a killer of DEF systems.

So, if the manufacturers had to provide an engine that used this and cleaned up the exhaust. And if the trucks had to be working correctly, no matter the conditions, why aren’t fuel companies required to provide bulk DEF year-round?  It is the industry standard to use DEF. Everyone else is held accountable except the fuel companies. Why?

Sure, you can buy DEF in single-use containers. How many straws does that equal? Fuel companies are in business to make money but so are we. Jug DEF is several times higher in cost per liter. I guess it’s easier to shut your pumps off and sell a product that will help your bottom line, but we don’t have that option.

Shame on all those fuel companies who haven’t come up with a year-round solution to provide bulk DEF. In over a decade. I try not to just write about problems. If I don’t have a solution, I try to figure one out. Here’s a simple solution. Hold fuel companies to our standards. If you sell diesel, you must provide bulk DEF.

DEF in jugs is so wrong environmentally and is far too expensive. Prices fluctuate but I calculated one time that jug DEF costs an extra $20 per day. It is shameful that over a decade later there are scores of empty plastic jugs littering our truck stops. This is one mandate I could get behind.

David Henry is a longhaul driver, Bell Let's Talk representative and creator/cohost of the Crazy Canuck Truckin podcast. His passion is mental health and presenting a better image for trucking to the public.


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  • Have the truck stops out in DEF heaters like our trucks have for years, and also put in a recirculating system. Can’t spend money on that I bet.

  • The DEF actually reduces the NOx, not soot or particulate. That’s done by the DPF, which has its own issues. As well as Exhaust Gas Recirc.

    Emission standards have substantially harmed Diesel engines.

    I like your comparison to indirect environmental impacts. Increase in waste stream, reducing engine life expectancy, and decreasing efficiency is something I don’t think the EPA takes into consideration. How much more NOx and soot is released due to the manufacture and delivery of DEF?

    Hopefully get realize this before diesels are killed for good.

  • collectively plan routes to bypass fuel stations without DEF or operational DEF. this could be implemented through one single route planning app driven by rig performance data and driver reports of DEF availability. collective negotiation with fuel companies may be another approach, but market forces more powerful.

  • I think we MIGHT have fixed one problem, the jury is still out on that, but we’ve created a lot more problems with DEF. You still have idiots who delete their trucks and jack with the fuel/air mixture and blow clouds of black smoke on people. Properly running diesels don’t smoke, except for maybe in super cold weather, and that’s just until the engine gets hot.

    But, beyond that, SOMETHING is killing off all the trees along side of the roads and highways. Back off the road 40 or 50 feet, you really don’t have a problem with multiple trees doing and falling over. Close to the roads, you’ve got serious problems. I heard once someone wonder if maybe Monsanto’s roundup isn’t evaporating and falling along with the rain water. But, if that were the case you’d expect there to be a uniform occurrence of trees dying and falling.

    I know I’ve read bunches of people who have always parked their trucks in certain places but now their truck has DEF, and now their trees and shrubbery is dying off. I’m thinking it’s the DEF causing it. I know it puts a nasty taste in your mouth if you catch a whiff of it.

    I don’t think diesel emissions were that big of a problem to start with. Gasoline engines produce the same gasses as diesels, but they don’t have to run scrubbers or aftertreatement fluids. I think what they should’ve done is went after the idiots who like to “roll coal” with their trucks. I think there should’ve been a crackdown on rolling coal intentionally and setting up your truck specifically to do it. I think those people should’ve been arrested for assaulting people if nothing else. Nobody wants a plume of black diesel smoke blown in their face. They should’ve been arrested, their trucks impounded, with really hefty fines and on top of that, they can’t get their trucks back until they pay the fines and fix their truck to not smoke.

    I think that would’ve been a far better solution. I know on my truck, a 2015 RAM 3500 that I bought used two years ago, I have yet to make it home without an exhaust code. I’ve spent thousands of dollars on repairs to my exhaust system and I still can’t make it home without an exhaust code after two years of ownership. But, deleting is illegal with ungodly fines. I need the truck, so what am I supposed to do?

      • Too much effort required to read his post, for a short attention span? His comment was relevant and non-redundant. You weren’t required to read it. Why bother to post such an unproductive criticism that is a complete red herring.

    • There’s a lot of problems with this comment here. First off there’s no such thing as an air/fuel ratio on diesel engines because they don’t give a toss about stoichiometry. And no, glyphosate isn’t killing any trees and isn’t even particularly dangerous as far as industrial chemicals go.
      And I’ll put your feelings and possible conspiracy theories to ease with the trees by asking that you look at how trees grow on the side of roads……they grow out and sideways because they want that free real estate for photosynthesis which causes them to become overextended and structurally unstable which makes them easy pickings for inclement weather.

    • First of all a “properly running and tuned diesel” will always smoke before producing nothing but heat learn something or stfu.. secondly “soot” or black smoke is by far better for the environment than the 4k degree heat def trucks put out regenning and that super amazing ammonia smell goin down the road that loves to come thru your vents.. mmmm ya that’s amazing isn’t it?.. ooh ooooh i personally love the corrosion def causes on exhausts, def pumps and the ground around them yaaa that’s beautiful but hey at least they dOnT bLoW bLaK sChmOkE lol clown

  • Truckers need to be smarter than this? We talk about how def is hurting the environment? How about ATA OR OOIDA making commercials 4 nationwide viewing to show the adverse affects? The environmentalists know how to traumatize the country over the smallest things? Time to repay them with their own mistake…. DEF

  • We never needed a separate fluid for SCR. Using fuel as a reductant technology has existed even before urea / DEF, and DEG is hardly a harmless compound and is energy intensive to make, requires lots of energy to produce, and as this article makes note of, isn’t well suited to cold temps, which diesels already struggle with.. HC-SCR exhaust treatment systems literally just use the same fuel as the engine does to catalytically reduce NOx emissions, and to a lesser degree, soot, particulates, and other VOCs like CO. There are also other technologies that are being stagnated on like ducted fuel injection “DFI” and passive regenerating catalytic multiple stage DPFs that wouldn’t require regeneration cycles. And as unpopular as it is, increasing the bypass ratio of EGR systems more and more as well as intercooling them also has a significant role in reducing all emissions without really needing to implement other dumb and complex technologies.

    Basically what I’m saying is that the technology out there exists to not need dumb things like DEF, or even SCR possibly if we were putting resources into developing new tech for ICE / diesel especially. But ever since we got this idea that battery technology was mature and after diesel gate, many industries have become complacent or outright unwilling to change their business models for ones that make more sense. It’s almost as if they are trying to accelerate the transition to electric even though we are far from ready for it. And no, I’m not against the transition to EVs, but we haven’t even been able to standardize charging, I don’t see megachargers at truck stops, and EV trucks can’t do long haul yet without a severe reduction in in payload capacity… among a plethora of other issues like cost parity. Why are we letting development of current gen tech languish? It seems counter productive to make such crappy systems that people delete them and you end up having worse emissions than you would if you didn’t try to kill the technology and serve a govt subsidized industry at every turn. Yes DEF is the worst and we should definitely be putting resources into developing way more efficient diesel engines and the technologies that can help clean up their exhaust. Doing that comes down to developing diesel engines with more efficient combustion and also developing better exhaust treatment technology, it’s a two part thing.

    Diesel trucks will be around for way longer than y’all think. So we need to pressure the industry to not be stupid about developing the technology we need.

    • Spoken like an experienced, educated driver and perhaps an engineer. As you are aware, laws are written by lobbyists (lawyers) and passed by legislators (usually lawyers), not by engineers or subject matter experts (though sometimes in consultation with). If the truckers or pickup owners want to fix the problem, they’ll have to use their trade associations (lobbyists) or address or address the issue directly with legislators. Unfortunately, laws often result from who has the lobbyists with the deepest pockets or loudest voices in government. Unfortunately the fuel companies and enviros have more effective lobbyists, or at least louder voices.

  • Fire trucks in Canada are not exempt to the whole DEF thing. At least they weren’t in 2012 the last truck we bought with a 9 liter Cummins ISL motor. This thought of a shut down used to keep me awake at night, until we specified a bypass mode. The first time we went to engage the pump we had to jump a sensor. 500k$ and we were splicing wired on day one. Too much electronics on equipment today.

    • I don’t know where you live at but they sell it right at the pump where I live they have to keep it covered up so it doesn’t freeze

  • Why not have your own bulk def and pump? Not the solution for long haulers but if you have a fleet and a home base it has gotta help.

  • Yes I have a truck that has def on it So right the cost of def. And def brake downs it’s just a matter of time your company. Will be broke cost cost cost

  • Def has nothing to do with black soot reduction which is handled and stopped in its tracks by a sound DPF filter which was mandated starting in 2008. In 2010 DEF was added additionally to the emission system and the injected Def fluid reacts in the SCR (selective catalytic reaction) oxidization catalyst to reduce and actually almost fully eliminate NOX completely in a properly operating system. Diesel exhaust soot and Nitrogen oxides are both very harmful substances to humans and the enviroment. So in review soot is first fully eliminated then NOX is treated and reduced to almost zilch. 37 years truck coach mechanic oem trained and also an az driver from age of 18. —-Dieseldog!

  • You for got something DEF all so puts acid in the air an water that drips is toxic converters on cars an trucks the same test the water dripping out of an exhaust bad for ya old school equipment way better for the tree huggers

  • Mechanic here. All of this emissions horseshit is just smoke and mirrors. Jeff Bezos couldn’t afford to hire me as a truck driver. What idiot wants to put up with all of the nonsense and the a——s on the road?

  • Hi I been driving truck since 1990 and this emission clean air part costing me a money while others making money ,def is evil way making more money for oil companies notting more ,

  • DEF is unnecessary. If you keep your rpm range above 1500, it allows the temp to become high enough to burn the particulates. It was never used to stop the black soot as that can still be programmed into it. That is merely an over dump of diesel into the combustion chamber.
    Fuel companies also don’t like it. I worked for a major one and it hindered us also.
    Let’s talk environmental issue. It is adding another chemical released into the air on top of that of the carbon. Just because you can’t see the black doesn’t mean it isn’t still there. You are literally turning a liquid solid into a gas. It just doesn’t disappear like our idiotic government would like you to believe. Kinda like water, although that is a different story, how can we ha e a water shortage? Where is it going? Everything that was still is. It can’t just get up and leave our planet so let’s stop being stupid.
    Plainly said, if the Government says we need it, it is bad. Period.

  • Desperate I need to delete bypass something system to get around this Ford super duty truck I have stuck in San Jose del Cabo never coming back to America do you know where I could purchase a bypass delete kit thank you

  • All of that technology is a scam, I lost over $60.000 on repairs and time down all because of the Def system, not fair.

  • Regarding the Def issue, if I am not mistaken most of the DEF is manufactured in China . If that is true it is another product that benefits them. Recently went into local wal mart and no DEF to be found.

  • I will never own a truck newer than 2009 . A truckers voice is only heard when we all park our trucks until somebody wakes up and corrects the problems.

  • I hate DEF because environmental issues are not a priority in my life. I love the smell of diesel fuel in the morning. And, I love the taste of exhaust fumes with my pancakes. I say to you sir “Hell to the NO” DEF ELD SUCK. Oh buy the way, have a blessed evening. ☮️

  • Every tech advance using science is a makework project for profit as short term goals on a specific issue are accomplished but 10 more problems occur because of that one goal fix. If DEF and exhaust catalyst system saves environment by using more fuel, making engines run poorly in limp mode 30% of the time and completely destroying engines prematurely and having incorrectly dosed DEF system causing ammonia off gassing effect into drivers cabs and into the environment then i’d love to see how they calculate the parameters to environmental positive effects !!! Thier math is all wrong and the only thing positive out of this mandatory system is Thier bank accounts !!! Something like covid and their vaccines available the only positive is the profit margin in Thier bank accounts same scam different product !!! And now we can’t fix diesel so onto the next disaster electric trucks running in winter states and absorbing road salt spray into electrical circuits and not to mention high RF exposure for drivers because of huge amps of power required for hauling and super charging as well !!! Science a Make work project for profit $$$

  • I truly agree with your point. As a mechanic I can’t count the number of call outs for DEF system related problems in the early years. They did drop somewhat as the years past but the system is still a major pain and as for the pumps that provide bulk you are again correct. The fuel companies should be held accountable for the provision of cleaning up all the jugs if they cannot keep their pumps apperatoperational.

  • Thanks for this fabulous article, I own a 2016 GMC Canyon with a 2.8 l duramax diesel, although overall it’s a great truck the DEF system sucks. I’ve replaced my DEF pump at 90,000 km. And now this past winter we’ve experienced a few days in the minus 20 Celsius range and had issues with some sensors. We live in southwestern Ontario, temperatures aren’t really that cold. I can rent all kinds of diesel powered equipment and brand new stuff at that and none of it requires DEF. Why is this possible

  • A def plastic line froze/broke on my motorhome and derated in the mountains, cost 2 days, $700. Last year the def level sensor failed cost me $3,000 to have replaced. Found that the urea slowly eats away the level sensor to the point of failure. Had to purchase the complete level unit and was difficult finding a replacement.

  • They ruined gasoline by adding Ethanol.
    They ruined diesel fuel by going to ultra low sulfur. Truck diesel engines hardly go over 300,000 miles anymore before needing an overhaul. And look at the expense added to the cost of of an engine with added sensors and catalytic converters and regeneration. They only cause trouble. Truckers got enough trouble already even without these added problems. They should have left them alone. Everything was better back thEn. Now it sucks to be a trucker. Every time I see a big truck go by I have to think ” poor bastard “. I feel your pain.

  • I totally agree it’s a shame that we absorb the problems and cost trying to comply with the EPA yet the deleted criminals are able to get bye illegally in essence cuting costs so they can keep running and suppressing freight rates. Making it more difficult for law abiding truckers to compete on a level playing field. It’s fine for government to commit to a cleaner environment but the people who vote them in should also be the one’s incurring the cost Hence by freight rates to cover the increased cost of moving it

  • Emissions requirements are totally arbitrary. On the open road NOx from vehicles makes no difference for air quality. In the city diesel makes smog. Fuel companies that want your business will be reliable suppliers of DEF.
    The government is to blame for trying to appear green while officials carry on their dirty lifestyles.

  • I’d like to see bulk Def on the non commercial side as well I drive a diesel and respect truckers but with shortages and not being able to get box’s or jugs and I’d rather not send more to the landfill I feel bad about taking up a Trucker lane especially without a trailer just to get the crap. I haul heavy loads and such so a diesel is a nice tool to have .

  • I totally agree with you but the truth is that DEF started from California and It’s been made for not across North American continent and few manufacturers have been doing the engineering on the engine with out DEF has CAT and CUMMINS made engines for the northern states and has exception of DEF has the older sister DPF and if you want it u may buy an older truck’96 or older and u are able to get a brand new engine for manufacture for this
    But any dealer would not talk about this because losing too much money in labor and parts because it’s known that DEF it’s not good enough and has to many problems from manufacturing lines
    One burned cost between 3-9k and sensors and connectors made in Mexico and China is not working in winter more the 6 months so far the only people it’s suffered from this is the owners and drivers the rest makes millions of dollars and 4 years ago has determined the DEF it’s more damaging the environment than with out this and it’s was going against it to Supreme Court of USA but in Canada we don’t have the balls to make a move we are the puppies of big Brother!!!!

  • In total agreement….. but then again, aren’t all fuel companies legal gougers?
    And our politicians deaf, dumb and blind to the antics. Almost like they get kickbacks.

  • After 36 years of trucking being everything I loved, the 2013 DD15 was the one that finally broke me and drove me to quit trucking. Among other reasons, but that started my hatred.
    It was soooo bad it was actually making me feel suicidal.
    Then I ran other brands. same results. JUNK.

    Now I’m an employee at a gold mine as an equipment operator. Last year and a half my new Cat loader has been trouble free. I actually started thinking “maybe Cat off road has this emissions stuff figured out.” Well, only took a few days of minus 40 and the loader is shut down with all kinds of emission system fault codes, Toromont Cat is too busy to get up to fix it, and now the mine is buried in snow because I have no running machines to clear it.
    I got rid of all my diesel pickup trucks. Expensive, troublesome nightmares.

    And now my compact and farm tractors at home……I will NEVER own ANYTHING with DPF/DEF/SCR. I purposely only buy new Kubota’s that are 26 h.p. and under to avoid the emissions and everything bigger I have is antique 1955 models that run every time no matter what.

    Again, I will never ever buy anything new ever again with an emission engine. NEVER!!!!

  • David, I agree with you that bulk DEF should be available year round. I worked with a company that had bulk DEF at their home terminal and everyone carried “refilled” plastic 10 litre bottles which was actually cheaper than bulk at the truck stops.

  • DEF jugs don’t have to be single use. I was forced to buy two jugs coming back east from Winnipeg one time. So I just kept the empty jugs and refill them in the yard for any time I think I might need more on the road. Two jugs fit nicely under passenger side (non air) seat

  • drop def , and get on with it and all the other junk thats put on the engine , hands off gov , truckers need to make money

  • Farmers need a winter def exception.

    In the winter tractors are used for snow removal or feeding livestock.

  • Thank the ones who think “Rolling Coal” is cool. A few bad eggs ruin it for everyone. Been driving for 20 years professionally and I’d never be a owner operator due to trucks being down for months sitting at dealerships over the emission systems. I own a 03 Ram 3500 cummins and wont ever get anything newer than that due to egr valve, particulate filter and DEF. Ive seen enough trucks catch fire over the particulate filters on the sides of highways. Im sure burning up trucks pollute a heck of a lot more than what the exhaust would have done without it….

  • I rather see soot than not knowing what’s coming out of the tail pipe. The re-gen process burns gallons of diesel fuel, so what’s the cost savings on the environment? The impact of all those plastic containers, I assume being recycled? New diesel truck burn more fuel per mile at an economic, environmental cost, that over shadows the old more fuel efficient diesels of yesteryear.