These codes belong to an individual-cylinder fuel correction: a diesel's cylinder balance control measures each cylinder's crankshaft acceleration and adjusts its injection quantity; on petrol engines a cylinder-selective mixture control does the same. CARB requires the system to report when such a correction has used up its range or one cylinder causes an imbalance. P029C means the module attributes the deviation of cylinder 1 to an injector delivering too little – deposits or a sticking nozzle needle. GM's 2.8 litre Duramax lists it as a stuck-injector fault in its cylinder balance system, which then switches the balance control off. GM and Ford use other codes for this (P0263 ff, P219A ff); no manufacturer document describing this code with thresholds was found, so the description follows CARB and published patents.
Medium severity. Can I keep driving?Drive as little as possible and go to a repair shop. If you smell fuel or the engine is shaking badly, do not keep driving.
Cylinder 1 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light on
- Rough idle, vibration
- Lack of power, higher consumption or smoke
Most likely causes
- Deposits or coking at the nozzle of cylinder 1
- Nozzle needle sticking
- Contaminated fuel or water
- Injector circuit high-resistance
- Compression loss mimicking low output
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P029C means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 2: Fuel injection
- 9C: Specific fault in that system
Frequently asked questions
Can I keep driving with code P029C?
Drive as little as possible and go to a repair shop. If you smell fuel or the engine is shaking badly, do not keep driving.
What causes code P029C?
The most common causes are: deposits or coking at the nozzle of cylinder 1; nozzle needle sticking; contaminated fuel or water.
Related codes
- P029ACylinder 1 - Fuel Trim at Max Limit
- P029BCylinder 1 - Fuel Trim at Min Limit
- P029DCylinder 1 - Injector Leaking
- P0263Cylinder 1 Contribution/Balance
- P02CDCylinder 1 Fuel Injector A Offset Learning At Max Limit
- P0201Cylinder 1 Injector A Circuit/Open
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.