how to fix P0300 misfire code in BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

• Gather required tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to avoid electrical shorts.

2. Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coils from the spark plugs.
  3. Use a spark plug socket and ratchet to remove the old spark plugs.
  4. Inspect the old spark plugs for wear and ensure the new plugs are gapped to manufacturer specifications.
  5. Install the new spark plugs and torque them to the specification (usually around 20 Nm).
  6. Reconnect the ignition coils.

3. Check and Replace Ignition Coils

• Sub-steps:
  1. If misfire persists, remove the ignition coils.
  2. Inspect for cracks or signs of arcing; replace any faulty coils.
  3. Install new ignition coils and make sure they are securely fastened.
  4. Reconnect all electrical connectors.

4. Inspect and Test Fuel Injectors

• Sub-steps:
  1. Disconnect the fuel injector connectors.
  2. Use a noid light to check for electrical signals to the injectors.
  3. Replace any injectors that fail the test or show signs of failure.
  4. Reconnect all fuel injectors and connectors.

5. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses and connections.
  2. Use a smoke machine or carburetor cleaner to identify any leaks while the engine is running.
  3. Replace any damaged vacuum hoses.
  4. Ensure all connections to the intake manifold are tight.