The control module detected that the air-fuel mixture stayed richer than the target despite full corrective control (Fuel Control System B).
TuningBot DTC Database · v4.37.15
P21F5 Fuel Control System B Too Rich Off Idle Bank 1
Generic (OBD-II) interpretation in the TuningBot DTC database.
What P21F5 means
Related and nearby codes
How to read P21F5
Powertrain: engine, transmission and driveline systems.
Generic SAE-standard code: same meaning on every make.
Specific fault index within the subsystem.
Frequently asked questions about P21F5
What does P21F5 mean?
Fuel Control System B Too Rich Off Idle Bank 1. The control module detected that the air-fuel mixture stayed richer than the target despite full corrective control (Fuel Control System B).
Is P21F5 generic or manufacturer-specific?
P21F5 is a generic OBD-II code: it has the same meaning on every make and model that follows the SAE standard.
Can TuningBot remove P21F5 at file level?
If the fault logic lives in the ECU calibration, yes: our DTC Removal file service disables the specific fault entry. Checksum correction is not included: it is a separate, optional service. Not sure whether your case qualifies? Request a free assessment and our engineers will check your ECU file.
Other file services
Understand the system behind this code: Diagnostic Strategy and DTC Logic
