P021C
Cylinder 9 Injection Timing
Fuel injection timing
Generic OBD-II
High
What it means
P021C means the fuel injection timing for cylinder 9 is incorrect — the injection event for that cylinder isn't happening when the ECM commands it. It's most often seen on diesel and direct-injection engines. Mistimed injection makes cylinder 9 contribute poorly, so the engine can run rough, knock, or lose power.
High
Can I keep driving? Limited — incorrect injection timing on cylinder 9 makes the engine run rough and down on power; drive gently and get it diagnosed soon.
Common symptoms
What you'll notice
- Check-engine light on
- Rough running or a misfire-like stumble
- Reduced power
- Possible knock or diesel-like combustion noise
Common causes
Most likely first
- Worn or faulty cylinder 9 injector, or one needing recalibration/codingLikely
- Fuel delivery problem affecting cylinder 9 (pressure or contamination)Common
- Damaged wiring or connector at the injectorCommon
- Fault in the ECM's injector control for that cylinderLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame and any injector correction (IQA/coding) data for cylinder 9.
- Inspect the cylinder 9 injector wiring and connector.
- Test or compare the injector's performance and coding against the other cylinders.
- Replace or recode the cylinder 9 injector if it's out of spec (follow the maker's procedure).
- Clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P021C?+
Short trips at light load are usually fine, but sustained rough running or knock can stress the engine. Have it diagnosed before hard driving.
Can I just clear P021C?+
The code returns if the injector or its timing fault isn't corrected. Injection-timing faults generally need proper diagnosis rather than just clearing.
Related codes
Often seen with P021C
Read & clear P021C yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX