AdBlue

📖 YOUCANIC Automotive Glossary

AdBlue (also called DEF — Diesel Exhaust Fluid) is a 32.5% urea solution injected into the exhaust stream of diesel vehicles where it reacts with NOx in the SCR catalyst, converting harmful nitrogen oxides into harmless nitrogen and water. The system monitors DEF quality, tank level, injection rate, and catalyst efficiency. When faults occur or the tank runs empty, EPA-mandated inducement progressively limits engine power and eventually prevents restart.

Common issues include DEF crystallization in the injector (especially in cold climates), contaminated DEF from improper storage, DEF quality sensor failures, and the inducement countdown activating after repairs if the system is not reset. The YOUCANIC UCAN-II’s AdBlue Reset function clears inducement timers, recalibrates level sensors, and resets SCR counters after service. Always use ISO 22241-compliant DEF and never fill the DEF tank with water or other fluids.