What does code P21F8 mean?

Q: What does code P21F8 mean?

Fuel Control System B Too Lean at Idle (Bank 1). P21F8 means the engine computer has detected that the fuel control system for Bank 1 is running too lean when the engine is at idle, so the powertrain control module has reached the limit of its ability to add fuel. The computer monitors short-term and long-term fuel trim values and sets this code when the long-term trim on Bank 1 exceeds a calibrated threshold at idle, indicating unmetered air or insufficient fuel delivery.

DTC codes / P21xx · Fuel and air metering / P21F8

P21F8Fuel Control System B Too Lean at Idle (Bank 1)

P21F8 means the engine computer has detected that the fuel control system for Bank 1 is running too lean when the engine is at idle, so the powertrain control module has reached the limit of its ability to add fuel. The computer monitors short-term and long-term fuel trim values and sets this code when the long-term trim on Bank 1 exceeds a calibrated threshold at idle, indicating unmetered air or insufficient 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.