What does code P21CD mean?

Q: What does code P21CD mean?

Reductant Quality Module Supply Voltage Low. P21CD indicates that the reductant quality module has detected a low supply voltage on its power circuit, meaning the module is not receiving the voltage it needs to operate correctly. The engine control module sets this code when the supply voltage at the reductant quality module falls below the calibrated threshold for a set period of time.

DTC codes / P21xx · Fuel and air metering / P21CD

P21CDReductant Quality Module Supply Voltage Low

P21CD indicates that the reductant quality module has detected a low supply voltage on its power circuit, meaning the module is not receiving the voltage it needs to operate correctly. The engine control module sets this code when the supply voltage at the reductant quality module falls below the calibrated threshold for a set period of time.

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.