What does code P21A3 mean?

Q: What does code P21A3 mean?

Cylinder 8 Air-Fuel Ratio Imbalance. P21A3 indicates that the powertrain control module has detected an air-fuel ratio imbalance on cylinder number 8, meaning that cylinder is not contributing its share of power or is burning a mixture that is significantly richer or leaner than the rest of the engine. The computer typically makes this determination by comparing crankshaft speed fluctuations or individual cylinder fuel trim corrections against the other cylinders.

DTC codes / P21xx · Fuel and air metering / P21A3

P21A3Cylinder 8 Air-Fuel Ratio Imbalance

P21A3 indicates that the powertrain control module has detected an air-fuel ratio imbalance on cylinder number 8, meaning that cylinder is not contributing its share of power or is burning a mixture that is significantly richer or leaner than the rest of the engine. The computer typically makes this determination by comparing crankshaft speed fluctuations or individual cylinder fuel trim corrections against the other cylinders.

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.