P021BCylinder 8 Injection Timing
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P021B reports a fault in the injection timing of cylinder 8 on a diesel engine. Unlike P01D9/P01DA ('over retarded/advanced', the result of the injector learning routine in overrun), this code has no direction, and what it checks is up to the manufacturer. GM uses it as an electrical check on the 6.6 litre L5P Duramax V8: at every injection the engine module measures how long the injector current takes to reach its pull-in level of 13 A. If on the V8 that time is outside 60–150 µs in 10 of 20 samples, the code sets and the warning light comes on in the first trip. For 2020–2021 Silverado/Sierra HD, GM issued a software update against false setting. FCA's V6 and Ford do not use it.
- What you may notice
- Check engine light on
- Rough running or misfire, rough idle
- Loss of power, smoke or knocking possible
- Likely causes
- LikelyInjector of cylinder 8 faulty (coil, armature, wear, deposits)
- PossibleInjector wiring or connector: contact resistance, corrosion, chafing
- PossibleEngine software sets the code falsely (update available for some models)
- RareInjector driver stage or boost voltage in the engine module
- RareWrong injector code, contaminated fuel or loose injector clamp
- 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: €100 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.