P21F1Cylinder 11 Injector B Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21F1 describes a cylinder 11 B injector circuit that sits too high, i.e. its switched side is shorted to supply. The code exists in SAE J2012 for completeness of the cylinder series, but no public manufacturer source uses it, and no twelve-cylinder engine with two injectors per cylinder could be documented. CARB still requires an emission-relevant output to be checked for circuit faults, while allowing makers to combine fault types; a system could therefore report this short under the open code P21D9 instead. Electrically, a short to power keeps the injector from opening and loads the driver each time it switches. GM's LT5 V8 shows typical criteria for the same fault type, 0.5 Ohm or less to power in the driver-off state, Type A. Low fault: P21F0; A injector high: P0292.
- What you may notice
- Check engine light on
- Cylinder 11 lean or misfiring (P0311)
- Likely causes
- LikelyControl wire of the cylinder 11 B injector shorted to power
- PossibleInjector coil shorted
- RareControl module driver damaged
- 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.