What it means
The control module detected fuel leakage from the cylinder 1 injector. The code identifies leakage but does not establish whether the nozzle, seal, or another part is responsible.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The control module monitors cylinder 1 injector behavior and engine response for evidence that fuel continues to leak into that cylinder. P029D sets when it detects leakage, but does not by itself distinguish a leaking nozzle or valve from a seal, seat, pressure, or control problem.
Common causes
Most likely first.
- Injector nozzle or internal valve leaking
- Injector seal or seat leaking
- Injector stuck open or control fault
- Excess fuel pressure
Symptoms
- Check-engine light
- Rough idle or engine vibration
- Misfire or hesitation
- Fuel odor or increased fuel consumption
How to diagnose it
- Review freeze-frame data and cylinder 1 misfire or fuel-trim information, and check for related fuel-pressure codes.
- With the engine off, inspect the cylinder 1 injector area and connector for fuel, damage, or a loose connection; follow fuel-system safety precautions.
- Check whether cylinder 1 shows signs of excess fuel after shutdown using the manufacturer’s specified leak test.
- Measure fuel pressure and injector control behavior against the manufacturer’s procedure to separate excessive pressure from an injector fault.
- If the injector is leaking externally or internally, inspect its seal and seat as well as the nozzle and valve before selecting a repair.
Common fixes
- Repair a damaged cylinder 1 injector connector or control wiring if testing identifies it.
- Correct fuel pressure if it exceeds the manufacturer’s specification.
- Replace a failed cylinder 1 injector seal or repair the seat if leakage is confirmed there.
- Replace the cylinder 1 injector if its nozzle or internal valve is confirmed to leak.
Can I keep driving?
If there is a strong fuel smell, visible leakage, or severe misfiring, stop driving because leaked fuel can create a fire hazard and damage the catalytic converter. With milder symptoms, avoid extended trips and have the cylinder 1 leak checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.