What does code P21C6 mean?

Q: What does code P21C6 mean?

Reductant Level Sensor B Stuck. P21C6 indicates that the powertrain control module has detected a stuck condition in the reductant level sensor B circuit, which is part of the diesel exhaust fluid system on selective catalytic reduction equipped vehicles. The sensor signal remains fixed within a narrow range despite changes in fluid level or vehicle operation, so the computer cannot trust the reading for emissions control.

DTC codes / P21xx · Fuel and air metering / P21C6

P21C6Reductant Level Sensor B Stuck

P21C6 indicates that the powertrain control module has detected a stuck condition in the reductant level sensor B circuit, which is part of the diesel exhaust fluid system on selective catalytic reduction equipped vehicles. The sensor signal remains fixed within a narrow range despite changes in fluid level or vehicle operation, so the computer cannot trust the reading for emissions control.

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.