29D1
Moderate29D1 — Cylinder 5 Misfire (BMW Code 29D1)
Description
What the Code Means
29D1 logs a misfire in cylinder 3. The cause usually lies with the ignition components — coil or plug — or in the control unit itself. The diagnostic logic is simple: if swapping the coil and plug moves the misfire to another cylinder, the component is bad; if the misfire stays on cylinder 3, suspect the DME.
Symptoms
Symptoms
- rough idle, engine shaking;
- power loss, hesitation under load;
- check engine light on.
Causes and fixes
Diagnosis and Repair
- Swap the coil and plug from cylinder 3 to another cylinder. If the misfire follows them, the component (coil or plug) is faulty and should be replaced.
- If the misfire stays on cylinder 3, suspect the DME.
- Bench-test the DME ignition outputs.
- Repair or replace the DME ignition driver circuits.
Possible secondary damage
Secondary Damage
- catalytic converter damage — unburned fuel burns off in the catalytic converter;
- oxygen sensor contamination;
- higher fuel consumption. Don't ignore a misfire: the fallout reaches expensive components.