P21F2Cylinder 12 Injector B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21F2 is the generic code for a low circuit state, usually a grounded control wire, at the B injector of cylinder 12. It would need a twelve-cylinder engine with two injectors per cylinder, and none could be documented: the V12s from Lamborghini and Aston Martin inject into the ports only. No manufacturer publishes the code in this sense. One maker does use the number differently: McLaren bulletin KA-01931 lists P21F205 and P21F22F on the Artura, a V6 plug-in hybrid, as high-voltage battery faults (safety design current too low/high), repaired by replacing battery parts. On an Artura it is therefore a battery fault, not an injector fault. For a genuine injector fault, CARB's circuit monitoring applies, and GM's V8 criteria (ground short below 0.5 Ohm) are a guide. High fault: P21F3.
- What you may notice
- Check engine light on
- Misfire on cylinder 12 (P0312)
- Hybrid warning instead, if the code is a McLaren battery fault
- Likely causes
- LikelyCylinder 12 B injector wire shorted to ground
- PossibleInjector with internal ground fault
- RareManufacturer-specific use of the number (McLaren Artura high-voltage battery)
- 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.