What does code P21B8 mean?

Q: What does code P21B8 mean?

Cold Start Cylinder 3 Injection Timing. P21B8 indicates that the engine control module has detected an out-of-range condition in the cold-start injection timing strategy for cylinder 3, typically during the first few minutes after a cold start. The computer compares expected injection timing against actual feedback and sets the code when the deviation exceeds calibrated limits, often due to mechanical or electrical faults in the injector circuit or fuel delivery.

DTC codes / P21xx · Fuel and air metering / P21B8

P21B8Cold Start Cylinder 3 Injection Timing

P21B8 indicates that the engine control module has detected an out-of-range condition in the cold-start injection timing strategy for cylinder 3, typically during the first few minutes after a cold start. The computer compares expected injection timing against actual feedback and sets the code when the deviation exceeds calibrated limits, often due to mechanical or electrical faults in the injector circuit or fuel delivery.

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.