why does my BMW 3 Series G20/G21 (2019-2024) have a check engine light for P0301?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  • Disconnect the electrical connector.
  • Unscrew the ignition coil using the appropriate socket.
• Remove the spark plug using a spark plug socket:
  • Inspect the spark plug for wear, carbon buildup, or damage.
  • If necessary, replace with a new spark plug that meets OEM specifications (e.g., gap size).
• Reinstall the new spark plug and the ignition coil.

3. Inspect and Replace Ignition Coil

• If the ignition coil is found to be faulty:
  • Remove the old ignition coil.
  • Install a new ignition coil compatible with the BMW 3 Series G20/G21.
• Ensure proper seating and connection of the coil and reconnect the electrical connector.

4. Inspect Fuel Injector

• If the fuel injector is suspected to be clogged or faulty:
  • Remove the injector using appropriate tools.
  • Clean or replace the injector as necessary.
• Reinstall the injector and ensure all connections are secure.

5. Test and Reconnect Battery

• Reconnect the negative battery terminal.
• Start the engine and monitor for any misfire symptoms.