What does code P23F5 mean?

Q: What does code P23F5 mean?

Cylinder 4 Injector B Air-Fuel Ratio Imbalance. P23F5 indicates that the engine control module (ECM) has detected an air-fuel ratio imbalance specifically on cylinder 4, injector circuit B, meaning the fuel injector for that cylinder is not delivering the expected fuel quantity or the combustion event is not matching the other cylinders. The ECM monitors crankshaft speed fluctuations and oxygen sensor feedback to identify which cylinder is contributing to an imbalance, and it sets this code when the deviation exceeds a calibrated threshold.

DTC codes / P23xx · Ignition system and misfire / P23F5

P23F5Cylinder 4 Injector B Air-Fuel Ratio Imbalance

P23F5 indicates that the engine control module (ECM) has detected an air-fuel ratio imbalance specifically on cylinder 4, injector circuit B, meaning the fuel injector for that cylinder is not delivering the expected fuel quantity or the combustion event is not matching the other cylinders. The ECM monitors crankshaft speed fluctuations and oxygen sensor feedback to identify which cylinder is contributing to an imbalance, and it sets this code when the deviation exceeds a calibrated threshold.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.