how to fix a misfire on my BMW X3 G01 (2018-2024) with P0303 code

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before beginning repairs.

2. Inspect and Replace Spark Plug

1. Remove the engine cover if applicable.
2. Locate the ignition coil on cylinder 3.
3. Disconnect the electrical connector from the ignition coil.
4. Remove the ignition coil using a socket wrench.
5. Remove the spark plug using a spark plug socket.
6. Inspect the spark plug for wear or damage; replace if necessary.
7. Install the new spark plug, torque to manufacturer's specifications (usually around 18-22 ft-lbs).
8. Reinstall the ignition coil and reconnect the electrical connector.

3. Check and Replace Ignition Coil (if necessary)

1. If the spark plug appears fine, test the ignition coil for proper operation.
2. If faulty, replace the ignition coil with a new one.
3. Ensure to torque the coil to the specified value (typically around 8-10 ft-lbs).

4. Inspect and Replace Fuel Injector (if necessary)

1. If the ignition components are functioning properly, check the fuel injector.
2. Disconnect the electrical connector from the fuel injector.
3. Remove the fuel rail if necessary to access the injector.
4. Replace the injector with a new one, ensuring proper seating.

5. Reassemble and Reconnect

• Reinstall any components removed during the process, including the engine cover.
• Reconnect the negative battery terminal.