29D0

What the Code Means

Code 29D0 indicates a misfire in cylinder 4 of the N54 engine. A misfire occurs when the air-fuel mixture in the cylinder doesn't ignite properly. It can be caused by a faulty ignition system component (coil, spark plug), fuel system component (fuel injector), or mechanical problems. Diagnosis and causes are the same as for misfire codes in other cylinders.

Symptoms

• Engine: rough idle (running rough), loss of power, hesitation during acceleration
• Indicators: Check Engine Light (CEL) is on
• Conditions: symptoms may worsen under load or when the engine is cold

Diagnosis and Repair

Step 1: Read the Codes

Connect ISTA or INPA to confirm code 29D0 and check for related errors.

Step 2: Check the Ignition Coil

Swap the ignition coil from cylinder 4 to cylinder 1. If the fault code moves to cylinder 1, replace the coil (OEM 12138616153).

Step 3: Check the Spark Plug

If the misfire stays on cylinder 4, swap the spark plug from cylinder 4 to cylinder 1. If the fault moves, replace all spark plugs (OEM NGK 97506).

Step 4: Check the Fuel Injector

If the misfire persists, check the cylinder 4 fuel injector for leaks or clogging. If faulty, replace the injector (OEM 13537585261-12).

Step 5: Adaptation and Test Drive

After repair, clear adaptations and take a test drive to verify the fault is gone.

Secondary Damage

Ignoring code 29D0 can lead to:

• Catalytic converter damage from unburned fuel entering the exhaust system.
• Engine damage from prolonged operation with a severe misfire (possible overheating or mechanical damage).

Fix the fault as soon as possible to avoid costly repairs.