How to Clean and Protect Your Diesel Truck

How to Clean and Protect Your Diesel Truck’s SCR System

About 15 years ago, federal emissions standards set by the Environmental Protection Agency (EPA) mandated that diesel trucks emit lower levels of nitrogen oxide (NOx). To help reduce NOx emissions, a Selective Catalyst Reduction (SCR) system injects ultra-refined urea, known as diesel exhaust fluid (DEF), into the hot exhaust stream and filters it through a catalyst, converting harmful tailpipe emissions into nitrogen and water. Love it or hate it, your typical heavy-duty diesel truck sold in the United States dating back to about 2010 has a bucketful of SCR components and relies on DEF to stay running properly.

Albeit the obvious upside of the SCR system, as noted above, it’s not without its downsides: cost (high initial investment cost, and like diesel fuel, DEF has to be replenished regularly); complexity (the more systems on your truck, the more there is to leak, break, clog, fail, maintain, and so on); and the chance of the system throwing a code and triggering that good ’ol Check Engine light.

When it’s working correctly, you should never notice the SCR system (although you might complain about its existence), besides that white crust that forms after a sloppy DEF fill. What is that white stuff, anyway? These are crystal deposits formed when DEF breaks down and the water component evaporates, leaving a crystalized solid urea residue. Unfortunately, this is a representation of what can happen inside your truck. These crystals can build up inside your SCR system, damaging and clogging SCR components while eventually increasing fuel consumption and reducing engine power. Your truck can throw various OBD engine codes related to the SCR system (P20EE, P20EF, P204F, P207F, P20E8, and P218F) and even go into “limp” mode.

A few things cause or contribute to the buildup of crystalized urea inside the SCR system: leaks, which allow the de-ionized water to evaporate; lack of DEF or persistent low DEF, resulting in more head space that promotes evaporation and crystallization; improperly stored DEF, which can become contaminated and lose its proper ratio of de-ionized water to urea; bad DEF; and habitual low-speed, short-duration, light-load driving.

If you’re having trouble with your diesel truck’s SCR system or have noticed any of those engine codes, you need to start fighting those crystal deposits immediately. One of the easiest ways to take action is to add Rislone DEF Crystal Clean Diesel DEF & SCR Emissions System Cleaner (product number 4784) to a mostly full DEF tank to clean the system (including DEF injector and sender) of existing crystals. After dissolving these crystal deposits, keep the system clean and prevent new crystals from forming by adding Rislone Diesel DEF Treatment (product number 4780) every time you refill the DEF tank. Diesel DEF Treatment protects the tank, pump, heater, sender, lines, injector, reactors, and mixers. There’s a good chance these treatments will clear your P20EE and other SCR-related codes.

These made-in-the-U.S.A. Rislone products are specifically designed to safely and effectively treat SCR systems. Find Rislone wherever auto parts are sold.

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