BMW 535d xDrive corroded urea metering unit issue due to diesel fuel additive deterioration on BMW 535d xDrive

Some BMW 535d xDrive owners report experiencing issues related to a corroded urea metering unit, potentially caused by diesel fuel additive deterioration. These problems can lead to urea crystal build-up in the system, which affects components like the SCR Metering Valve and may result in performance issues due to clogging from dried crystals. Additionally, the deterioration of the diesel fuel additive can contribute to low power output and overall engine performance problems. While replacing the metering unit is relatively straightforward, requiring only the removal of a single panel, owners may need to troubleshoot the SCR metering module and metering cable for errors and resistance issues to effectively diagnose and resolve these concerns.