P21D9Cylinder 11 Injector B Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21D9 is reserved for an open circuit of the second injector on cylinder 11 and therefore only makes sense on twelve-cylinder engines with dual injection. No manufacturer documents this code publicly, and no available source names a twelve-cylinder engine that uses it. Its meaning follows from the series: like P21CF to P21D6, it is an electrical check of the injector drive, not of fuel quantity. CARB requires such circuit monitoring for injectors whose failure affects emissions; Ford's documented B-injector check for up to eight cylinders runs continuously above 11 V and needs 5 s, which shows the typical scale. If it ever appears, check the injector coil resistance and the harness first. The direct counterpart in the A series is P020B, the misfire code for cylinder 11 is P0311.
- What you may notice
- Check engine light on
- Misfire on cylinder 11 (P0311)
- Likely causes
- LikelyOpen coil in the second injector of cylinder 11
- PossibleDamaged injector harness or loose plug
- RareFaulty driver in the engine control module
- 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.