P21F0Cylinder 11 Injector B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21F0 is reserved for a low state, typically a wire touching ground, in the B injector circuit of cylinder 11. Setting it requires at least eleven cylinders with two injectors each, so in practice a V12 or W12 with combined port and direct injection. No such engine could be confirmed: Lamborghini's V12 family uses multi-point injection only, as do Aston Martin's V12 and Mercedes-AMG's M279. Accordingly no manufacturer documents the code. If a scan tool still shows it, check the cylinder count and whether the maker uses the number for something else. The generic logic follows CARB's circuit monitoring of output components; GM's V8 shows how it is usually judged (short to ground below 0.5 Ohm with the driver off). Open circuit: P21D9; high fault: P21F1.
- What you may notice
- Check engine light on
- Misfire on cylinder 11 (P0311)
- Likely causes
- LikelyCylinder 11 B injector wire shorted to ground
- PossibleInjector with internal short to ground
- RareCode read on an engine without a cylinder 11 B injector (scan tool or maker-specific use)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.