What does code P21B0 mean?

Q: What does code P21B0 mean?

Reductant Level Sensor C Circuit High. P21B0 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the signal circuit for the reductant level sensor 'C', which is part of the diesel exhaust fluid (DEF) level sensing system. The PCM expects the sensor's signal voltage to stay within a calibrated range, and a sustained high reading usually points to an open circuit, a short to voltage, or a failed sensor.

DTC codes / P21xx · Fuel and air metering / P21B0

P21B0Reductant Level Sensor C Circuit High

P21B0 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the signal circuit for the reductant level sensor 'C', which is part of the diesel exhaust fluid (DEF) level sensing system. The PCM expects the sensor's signal voltage to stay within a calibrated range, and a sustained high reading usually points to an open circuit, a short to voltage, or a failed sensor.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.