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

Solution

1. Preparation

• Gather tools and materials.
• Ensure the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coil connector for cylinder 1.
  3. Remove the ignition coil bolt using a socket set and carefully pull the coil out.
  4. Unscrew the spark plug using a spark plug socket.
  5. Install the new spark plug by hand to avoid cross-threading, then torque it to the manufacturer's specification (typically around 25 Nm).
  6. Reinstall the ignition coil and connector.

3. Replace Ignition Coil

• Sub-steps:
  1. If the spark plug does not resolve the issue, remove the ignition coil as described above.
  2. Install the new ignition coil by aligning it properly with the spark plug and pushing down until it clicks.
  3. Reconnect the ignition coil connector.
  4. Reinstall the engine cover if applicable.

4. Check Fuel Injector

• Sub-steps:
  1. Remove any necessary components to access the fuel injector for cylinder 1.
  2. Disconnect the fuel injector connector.
  3. Remove the injector using the appropriate tool, taking care not to damage the O-rings.
  4. Install the new injector and reconnect the fuel connector.
  5. Reassemble any removed components.

5. Perform Compression Test

• Sub-steps:
  1. Remove the spark plug from cylinder 1.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine for several seconds and record the reading.
  4. Compare the reading to the manufacturer's specifications (usually around 150-200 psi for a healthy cylinder).