P21D6Cylinder 8 Injector B Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21D6 is the highest B injector code that any manufacturer documents publicly: both Ford's port injector check (P21CF to P21D6) and GM's LT5 injection module list end here. On the LT5 the port injectors exist to add fuel under boost beyond what the direct system and its mechanical pump can deliver, so an open cylinder 8 injector shows up mainly at high load, where that cylinder can run lean and lose power; GM stores the fault as Type A from 20 failed samples out of 25 with at least 11 V on the powertrain relay. In GM's firing order cylinder 8 follows cylinder 1. On Ford's 5.0 V8 from 2018 it is the rear cylinder of the second bank and the check runs continuously for 5 s. The direct injector counterpart is P0208; P21D5 is cylinder 7.
- What you may notice
- Check engine light on
- Misfire or lean running on cylinder 8 under load
- Power loss at wide-open throttle
- Likely causes
- LikelyPort injector of cylinder 8 open
- PossibleWire damage at the rear of the engine near the firewall
- RareOutput of the engine or separate injection module failed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.