P21C1Cold Start Cylinder 12 Injection Timing
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Cylinder 12 is the last cylinder of V12 and W12 engines. Direct-injection V12 include Ferrari's F140 family (FF, F12berlinetta, 812 Superfast) and BMW's N74; among W engines there is the 6.3-litre W12 FSI. P21C1 reports that during the cold-start heating phase the injection timing of cylinder 12 deviated from its target. The code closes the series P21B6–P21C1, which exists because CARB requires cold-start faults to be kept apart from normal ones; the following code, P21C2, already belongs to the SCR reductant heater. No manufacturer publishes use of P21C1. Practical cross-checks: P021F (timing, warm engine), P0212 (injector circuit) and P0312 (misfire). Repairs on these engines are workshop jobs.
- What you may notice
- Check engine light after cold starts
- Hardly any drivability change, at most a slightly uneven cold idle
- Likely causes
- LikelyInjector of cylinder 12 with deposits or worn needle
- PossibleDamaged wiring at the end of the cylinder bank (injector 12)
- RareCold-start calibration of the engine module out of date
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €250 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.