What is DEF, and why is it important?

What is Diesel Exhaust Fluid?

Diesel Exhaust Fluid (DEF) is a mixture of ⅔ deionized water and ⅓ urea that is added to your diesel fuel via a separate tank and control system. DEF is meant to reduce the emissions from a diesel engine. If your diesel medium or heavy-duty pickup is newer than 2010, it has a DEF tank that you have to fill to keep the vehicle’s emissions within the federal standards and keep the vehicle street legal.

Monitoring Your DEF Levels

Because DEF volume is affected by so many factors, you’ll need to carefully monitor the level of DEF in your vehicle to avoid having your engine performance throttled since many vehicles with DEF systems will put the engine in limp mode or limit the number of times it can be started when you run out of DEF.

The EPA has very strict standards when it comes to diesel emissions, and so the manufacturer of your diesel truck has built-in systems and warnings to help you keep enough DEF in the tank to control your emissions. Many vehicles have gauges and warning lights to let you know when the DEF level is getting low. Some vehicles will put your engine in limp mode (reduced power) if you run out of DEF. Because DEF isn’t sold at every gas station, it’s important that you pay attention when the first warning light shows you the volume of DEF in your vehicle is getting low. Preparation and monitoring the warning signals will save you from getting stranded.

Pros and Cons of a DEF Compliant Vehicle

There are very few cons when it comes to owning a DEF vehicle. One is the up-front cost of the vehicle tends to be a bit higher than it would be without the DEF system. Another is that the related Selective Catalytic Reduction System may require more maintenance and repair than a vehicle without one, especially since the system is prone to clogging, which can create other engine problems.

The pros of a DEF vehicle are many, not the least of which is the emissions reduction the system creates. You’ll also get better fuel economy, more horsepower, and less engine wear.

No matter what type of diesel vehicle you drive, there will come a time when you need repairs for that vehicle. Why not stop by Cooper’s Auto Repair and Services to talk with our talented technicians, who are diesel repair experts, about what they can do to help you keep your diesel vehicle in top running order?

Written by Coopers Auto Repair Specialists

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