OBD-II code · Powertrain (generic, extended)
P21F2 Cylinder 12 Injector B Circuit Low
Cylinder 12 second-injector (B) drive line stuck low — short to ground. A flow-deviating injector throws off cylinder balance — adjacent cylinders run leaner/richer to compensate, often masking the root cause until the trim limit is hit.
Is it safe to drive with P21F2?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyShort to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- Parts involved
- Fuel Injector
Related codes
- P21DACylinder 12 Injector B Circuit/Open
- P21DBCylinder 1 Injector B Circuit Low
- P21DECylinder 2 Injector B Circuit Low
- P21E0Cylinder 3 Injector B Circuit Low
- P21E2Cylinder 4 Injector B Circuit Low
- P21E4Cylinder 5 Injector B Circuit Low
- P21E6Cylinder 6 Injector B Circuit Low
- P21E8Cylinder 7 Injector B Circuit Low
- P21EACylinder 8 Injector B Circuit Low
- P21ECCylinder 9 Injector B Circuit Low
- P21EECylinder 10 Injector B Circuit Low
- P21F0Cylinder 11 Injector B Circuit Low
- P21EFCylinder 10 Injector B Circuit High
- P21F1Cylinder 11 Injector B Circuit High
- P21F3Cylinder 12 Injector B Circuit High
- P21F4Fuel Control System B Too Lean Off Idle (Bank 1)
- P21F5Fuel Control System B Too Rich Off Idle (Bank 1)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.