What does code P21A1 mean?

Q: What does code P21A1 mean?

Cylinder 6 Air-Fuel Ratio Imbalance. P21A1 indicates that the powertrain control module has detected an air-fuel ratio imbalance on cylinder 6, meaning that cylinder is not contributing its expected share of power or exhaust oxygen content compared to the other cylinders. The computer monitors crankshaft speed fluctuations and/or oxygen sensor feedback to flag a consistent deviation, which typically points to a fuel delivery, compression, or ignition problem specific to that cylinder.

DTC codes / P21xx · Fuel and air metering / P21A1

P21A1Cylinder 6 Air-Fuel Ratio Imbalance

P21A1 indicates that the powertrain control module has detected an air-fuel ratio imbalance on cylinder 6, meaning that cylinder is not contributing its expected share of power or exhaust oxygen content compared to the other cylinders. The computer monitors crankshaft speed fluctuations and/or oxygen sensor feedback to flag a consistent deviation, which typically points to a fuel delivery, compression, or ignition problem specific to that cylinder.

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.