P029D
Cylinder 1 - Injector Leaking
Fuel & air metering
Generic OBD-II
High
What it means
P029D means the ECM has determined that cylinder 1's fuel injector is leaking — delivering more fuel than commanded. The extra fuel makes cylinder 1 run rich, causing rough idle, misfire, hard starting, and a fuel smell. Left unrepaired, the raw fuel can foul the spark plug, dilute the engine oil, and overheat the catalytic converter.
High
Can I keep driving? Drivable but risky — a leaking injector floods cylinder 1 with extra fuel, which fouls the plug, washes down the bore, and can harm the catalytic converter.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle, especially a rich-running or uneven idle
- Cylinder 1 misfire and hard starting (worse when warm)
- Fuel smell, black smoke, or fouled cylinder 1 spark plug
Common causes
Most likely first
- Leaking or failed cylinder 1 fuel injector passing excess fuelLikely
- Worn injector seat, tip, or O-ring/seal allowing fuel to seepCommon
- Excessive fuel pressure forcing extra fuel past the injectorCommon
- Faulty engine control module (ECM) — least commonLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame and check fuel-trim data for a rich condition tied to cylinder 1.
- Inspect the cylinder 1 spark plug for fuel fouling and the injector area for leakage.
- Perform an injector leak-down/balance test and verify fuel pressure is within spec.
- Replace the leaking cylinder 1 injector (and seals) if confirmed. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P029D?+
Only briefly. Raw fuel from a leaking injector can wash oil off the cylinder wall, foul the plug, and damage the catalytic converter, so repair it soon.
Can I just clear P029D?+
It clears, but the code returns because the injector keeps leaking until it is replaced.
Related codes
Often seen with P029D
Read & clear P029D 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