how to fix P0302 misfire code in BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, fuel injector cleaner.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the electrical connector from the ignition coil on cylinder 2.
3. Unbolt and remove the ignition coil using a socket.
4. Remove the old spark plug using a spark plug socket; inspect for wear or fouling.
5. Gap the new spark plug to manufacturer specifications and install it.
6. Reinstall the ignition coil and reconnect the electrical connector.
7. Reattach the engine cover if removed.

3. Inspect and Replace Ignition Coil (if faulty)

1. If the ignition coil tested bad, purchase a replacement coil compatible with the vehicle.
2. Follow the steps in the previous section to remove the faulty ignition coil.
3. Install the new ignition coil and reconnect the wiring harness.
4. Ensure all connections are secure and properly seated.

4. Clean or Replace Fuel Injector

1. If the fuel injector is clogged, use a fuel injector cleaner or remove it for inspection.
2. To clean, follow the manufacturer's instructions for the fuel injector cleaner.
3. If replacing, disconnect the fuel line and electrical connector from the injector.
4. Remove the old injector, lubricate the O-ring of the new injector, and install it.
5. Reconnect the fuel line and electrical connector.

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 for several seconds and record the compression reading.
4. Compare the result with manufacturer specifications; a significant drop may indicate internal engine problems.