What does code P21A5 mean?

Q: What does code P21A5 mean?

Cylinder 10 Air-Fuel Ratio Imbalance. P21A5 indicates that the powertrain control module has detected an air-fuel ratio imbalance on cylinder 10, meaning that cylinder's combustion is not contributing the expected amount of oxygen to the exhaust stream. The computer compares crankshaft speed fluctuations and upstream oxygen sensor feedback to identify which cylinder is misfiring or running at an incorrect air-fuel mixture.

DTC codes / P21xx · Fuel and air metering / P21A5

P21A5Cylinder 10 Air-Fuel Ratio Imbalance

P21A5 indicates that the powertrain control module has detected an air-fuel ratio imbalance on cylinder 10, meaning that cylinder's combustion is not contributing the expected amount of oxygen to the exhaust stream. The computer compares crankshaft speed fluctuations and upstream oxygen sensor feedback to identify which cylinder is misfiring or running at an incorrect air-fuel mixture.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

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.