Don’t overlook truck DEF filter importance

Say, “Aftertreatment,” and the next likely word in the word-association game is “DPF!” The diesel particulate filter bears the brunt of aftertreatment service blame. When there’s an aftertreatment-related service issue the first instinct is to run a DPF regen, but here’s the catch: A DPF regen won’t fix a problem related to the diesel exhaust fluid (DEF) system.

“Urea [a.k.a. DEF] injection is part of the aftertreatment system just like the DPF. They work together to reduce the NOx emission of a vehicle,” noted Donald Chilton, director, product management, Wix Filters. “If the injection isn’t working correctly, the regeneration process won’t work properly. This will lead to power loss and eventually a shutdown.”

Additionally, excessive pressure in the DPF could cause fuel economy to drop before leading to said power loss, Chilton said.

Your first line of DEF system defense is DEF storage. Keeping your DEF at temperatures between 20 and 80 degrees fahrenheit will help prevent DEF degradation and reduce the chances of experiencing a DEF quality issue. DEF also typically has a shelf life of around 12 months. Finally, technicians can use a refractometer to check the quality of the DEF to identify if the fluid has been contaminated and catch a potential problem before it occurs.

Once the DEF is filled in your truck, you’re going to want to think about filtration.

“Shockingly, diesel exhaust fluid is dirty even from the factory,” Chilton said. “When aftertreatment systems were first used, urea filters became necessary once the fact of dirty DEF was understood when vehicles stopped working.”

The urea filter is the defense for the Selective Catalytic Reduction (SCR) system. While the filter element has remained relatively constant throughout the years, the filtration media has become more advanced as aftertreatment systems have evolved. Today, DEF filtration media, like that offered by Wix Filters, aid in degassing and help to prevent crystals in the urea from passing through the aftertreatment system.

“This little filter protects the entire aftertreatment system from shutting down or malfunctioning,” Chilton said. “It is easy to overlook but literally takes a minimal amount of time to change out.”

Wix Filters recommends that urea/DEF filters are replaced every year or every 125,000 miles.

Visit the Wix Filters website for more information on heavy-duty filter solutions from Wix Filters.