how can I resolve the P0301 misfire code in my BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before beginning work.

2. Replace Spark Plug

• Remove the ignition coil cover if applicable.
• Unplug the ignition coil connector from the ignition coil in cylinder 1.
• Remove the ignition coil using a socket set.
• Extract the spark plug using a spark plug socket.
• Install the new spark plug, ensuring it is properly gapped (typically 0.032 inches for BMW).
• Reinstall the ignition coil and reconnect the connector.

3. Test and Replace Ignition Coil (if necessary)

• Use a multimeter to check the resistance of the ignition coil; it should be within the manufacturer’s specifications (consult the repair manual).
• If the ignition coil is faulty, replace it with a new unit.
• Reinstall the ignition coil and reconnect the connector.

4. Clean or Replace Fuel Injector (if necessary)

• Remove the fuel injector connector for cylinder 1.
• If cleaning, use an injector cleaning kit and follow the instructions to clean the injector.
• If replacing, detach the fuel rail (ensure fuel pressure is relieved first) and replace the injector.
• Reattach the fuel rail and connectors.

5. Final Reassembly

• Reconnect the negative battery terminal.
• Start the engine and allow it to idle while checking for any abnormal sounds or behavior.