HOLLY, Mich., April 16, 2025 (GLOBE NEWSWIRE) -- A diesel truck, car or SUV that is losing power and fuel economy, shutting down unexpectedly, and/or has a DEF warning light illuminated is probably suffering from a problem with its selective catalytic reduction (SCR) system, sometimes called its DEF system.

DEF stands for “diesel exhaust fluid,” also known by the brand AdBlue^®. It’s a chemical used in the SCR system of modern diesel vehicles to convert the harmful nitrogen oxides in vehicle exhaust into plain nitrogen and water. Here are four of the most common DEF problems and how to solve them.

Problem: Low DEF. The DEF warning light usually turns on or flashes to indicate there is not enough DEF in the system.

Solution: Refill the DEF tank. Regularly check and refill the DEF tank as needed. If the problem persists, the sensors could be damaged or there might be a leak.

Problem: Crystal deposits clogging the system. DEF consists of 32.5 percent liquid urea and 67.5 percent water. Under certain conditions, the water in DEF can evaporate, leaving behind white crystal urea deposits. Over time, these crystals can build up, clogging system components and interfering with normal operation.

Solution: Clean and treat the system to remove existing crystals and prevent new ones from forming. For the first time in North America, there are now chemical solutions that make it easy to remove urea deposits. New Rislone DEF Crystal Clean^® Diesel DEF & SCR Emissions System Cleaner cleans the entire system, dissolving white crystal urea deposits that form in the tank, pump, heater, sender, lines, injector, decomposition tube/reactor, and mixer. It clears P20EE and related OBD codes and restores system function. Once the system is clean, keep it that way with new Rislone DEF Treatment. It improves diesel exhaust fluid performance and prevents urea crystal deposits. Both products can be added directly to the DEF tank and won’t void manufacturer warranties.

Problem: DEF Contamination. Dirt, rust and other particles can cause abrasion on internal components. Having too much or too little water in the system can contribute to crystallization. Accidentally adding diesel fuel, coolant or engine oil to the DEF tank can result in significant damage.

Solution: Properly store and install DEF. Before adding DEF, thoroughly clean the vehicle fill cap and the area around it to remove any debris. Tightly seal the cap after filling to prevent water and dirt intrusion. Only use API-certified DEF that is clear, colorless and free of particles. Store DEF in a cool, dry area out of direct sunlight. Avoid transferring DEF to containers used to hold other chemicals or using a dirty funnel for installation. If other fluids are mistakenly added to the DEF tank, the vehicle should not be driven until the entire system has been drained, flushed and evaluated.

Problem: Frozen DEF. DEF freezes in temperatures below 12 degrees Fahrenheit. This is generally not an issue in a vehicle that is running because the DEF system’s heating elements activate automatically in low temperatures. DEF may freeze in storage or in vehicles that are parked.

Solution: Idle the engine to activate the DEF tank heater. Although the vehicle’s DEF warning light may illuminate when DEF is frozen, most vehicles are programed to operate normally while the DEF thaws. Freezing and thawing will not harm the fluid itself.

Learn more about protecting a diesel vehicle’s SCR and DEF systems, avoiding costly repairs and improving performance at Rislone.com/diesel-defense.

About Rislone

As a global leading engine treatment brand since 1921, Rislone has a long history of solving and preventing diesel engine issues. The company conducted years of research to develop its DEF solutions to help customers avoid expensive DEF and SCR system repair bills. Like all Rislone products, DEF Crystal Clean and Diesel DEF Treatment are made in the USA. Both work with all UREA DEF/ AdBlue^® fluids and will not void manufacturers’ new vehicle warranties. Rislone products are available where auto parts are sold. Based in Holly, Michigan, Rislone is ISO 9001 certified.

Photos accompanying this announcement are available at
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Media Contact:
Kristen Simpson
Simpson Communications, LLC
(216) 991-4297
kristen@simpsoncomm.com