how to fix P0302 code on my BMW 3 Series G20/G21 (2019-2024)

Solution

1. Preparation

• Tools Needed: OBD-II scanner, socket set, torque wrench, compression tester, fuel pressure gauge, noid light.
• Disconnect the battery to avoid electrical shorts.
• Allow the engine to cool down before starting work.

2. Replace Spark Plug and Ignition Coil

1. Remove the engine cover to access the ignition coils.
2. Disconnect the electrical connector from the ignition coil in cylinder 2.
3. Remove the ignition coil using a socket.
4. Remove and inspect the spark plug; replace it if worn or damaged.
5. Install the new spark plug and torque it to the manufacturer's specifications (usually around 18 ft-lbs).
6. Install the new ignition coil and reconnect the electrical connector.
7. Reinstall the engine cover.

3. Test and Replace Fuel Injector (if necessary)

1. If the ignition components are functioning correctly, use a noid light to test the fuel injector pulse.
2. If the injector is not firing, replace the fuel injector in cylinder 2.
3. Remove the fuel rail and disconnect the injector connector.
4. Replace the faulty injector and reconnect all components.
5. Reinstall the fuel rail ensuring proper sealing.

4. Compression Test (if misfire persists)

1. Remove the spark plug from cylinder 2.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine a few times and record the compression reading.
4. Compare the reading to the manufacturer's specifications. If low, further investigation into valve or piston issues may be needed.