What does code P21F3 mean?

Q: What does code P21F3 mean?

Cylinder 12 Injector B Circuit High. P21F3 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the control circuit for injector B on cylinder 12, which usually means the circuit is open, shorted to power, or the injector's internal coil has failed. The PCM commands a ground pulse to fire the injector, and when it sees the circuit voltage stay high instead of dropping as expected, it flags this fault and may disable that injector to protect the driver circuit.

DTC codes / P21xx · Fuel and air metering / P21F3

P21F3Cylinder 12 Injector B Circuit High

P21F3 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the control circuit for injector B on cylinder 12, which usually means the circuit is open, shorted to power, or the injector's internal coil has failed. The PCM commands a ground pulse to fire the injector, and when it sees the circuit voltage stay high instead of dropping as expected, it flags this fault and may disable that injector to protect the driver circuit.

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.