OBD-II code · Powertrain (generic, extended)
P21A5 Cylinder 10 Air-Fuel Ratio Imbalance
Cylinder 10 fuel trim deviates significantly from the bank average — a single-cylinder injector or intake fault.
Is it safe to drive with P21A5?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyInjector clogged or leaking
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- Parts involved
- Fuel Injector
Related codes
- P219CCylinder 1 Air-Fuel Ratio Imbalance
- P219DCylinder 2 Air-Fuel Ratio Imbalance
- P219ECylinder 3 Air-Fuel Ratio Imbalance
- P219FCylinder 4 Air-Fuel Ratio Imbalance
- P21A0Cylinder 5 Air-Fuel Ratio Imbalance
- P21A1Cylinder 6 Air-Fuel Ratio Imbalance
- P21A2Cylinder 7 Air-Fuel Ratio Imbalance
- P21A3Cylinder 8 Air-Fuel Ratio Imbalance
- P21A4Cylinder 9 Air-Fuel Ratio Imbalance
- P21A6Cylinder 11 Air-Fuel Ratio Imbalance
- P21A7Cylinder 12 Air-Fuel Ratio Imbalance
- P21A8Reductant Level Sensor B Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.