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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, noid light.
• Clear any stored trouble codes from the ECU using the OBD-II scanner before starting repairs.

2. Replace Ignition Coil (if faulty)

1. Disconnect the negative battery terminal to avoid electrical shorts.
2. Remove the engine cover if applicable to access the ignition coils.
3. Unplug the electrical connector from the ignition coil for cylinder 2.
4. Remove the bolt securing the ignition coil using a socket wrench.
5. Gently pull out the ignition coil from the spark plug well.
6. Install the new ignition coil by reversing the removal steps, ensuring it is seated properly and secured with the bolt.

3. Replace Spark Plug (if faulty)

1. Use a spark plug socket to remove the spark plug from cylinder 2.
2. Inspect the old spark plug for wear and fouling; check the gap with a feeler gauge.
3. Install a new spark plug with the correct specifications, ensuring the gap is set properly (typically around 0.028-0.032 inches for BMW).
4. Torque the spark plug to the manufacturer’s specified value (usually around 23 Nm).

4. Test Fuel Injector Operation

1. Connect a noid light to the fuel injector connector of cylinder 2.
2. Crank the engine and check if the noid light flashes, indicating that the injector is receiving a signal.
3. If it does not flash, check the wiring and connector for damage.
4. If the injector is faulty, remove and replace it following similar steps to the spark plug replacement.

5. Perform Compression Test

1. Remove the spark plug from cylinder 2.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine and record the compression reading.
4. If the compression is low, further investigation may be needed (e.g., valve issues, head gasket).