how to fix P0303 misfire code in BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather necessary tools and parts required for the repair.
• Disconnect the vehicle battery to ensure safety.
• Allow the engine to cool before proceeding with repairs.

2. Inspect and Replace Spark Plug

1. Remove the engine cover to access the ignition components.
2. Disconnect the ignition coil connector for cylinder 3.
3. Remove the ignition coil using a socket set.
4. Extract the spark plug using a spark plug socket.
5. Inspect the spark plug for wear (fouling, damage) and replace if necessary with OEM specifications (typically NGK or Bosch).
6. Install the new spark plug to the manufacturer's torque specifications (generally 15-20 Nm).

3. Inspect and Replace Ignition Coil

1. If the spark plug is in good condition but the misfire persists, replace the ignition coil for cylinder 3.
2. Install the new ignition coil and ensure it is seated properly.
3. Reconnect the ignition coil connector.

4. Check Fuel Injector

1. If the misfire continues, inspect the fuel injector for cylinder 3.
2. Remove the fuel injector connector and use a multimeter to test for proper resistance.
3. If faulty, replace the fuel injector with an OEM part.
4. Reconnect the fuel injector and ensure it is properly seated.

5. Final Assembly

1. Reinstall the engine cover and reconnect the vehicle battery.
2. Clear the trouble codes from the ECU using an OBD-II scanner.