how to fix P0301 misfire code in BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

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

2. Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  • Use a socket set to remove the bolts securing the ignition coil.
  • Gently pull the ignition coil out to avoid damage.
• Remove the spark plug:
  • Use a spark plug socket to unscrew and remove the spark plug from cylinder 1.
• Install the new spark plug:
  • Ensure the new spark plug is gapped to manufacturer specifications.
  • Insert the spark plug and torque it to the manufacturer's specification (typically around 15-20 ft-lbs).
• Reinstall the ignition coil:
  • Apply dielectric grease to the ignition coil boot for better sealing.
  • Secure the ignition coil back in place with the bolts.

3. Check and Replace Ignition Coil (if necessary)

• If the ignition coil appears faulty during inspection:
  • Remove the faulty ignition coil as described above.
  • Install the new ignition coil, ensuring it's seated properly.
  • Reconnect the electrical connector securely.

4. Clean or Replace Fuel Injector (if necessary)

• If the fuel injector shows signs of clogging:
  • Remove the fuel rail to access the injector.
  • Use a fuel injector cleaner or replace the injector if cleaning is insufficient.
  • Reinstall the fuel rail and ensure all connections are tight.

5. Final Assembly

• Reconnect the negative battery terminal.
• Start the engine and check for any abnormal noises or issues.