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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety.
• Allow the engine to cool down before starting work.

2. Replace Spark Plugs

• Remove the engine cover if applicable.
• Use a socket wrench to remove the spark plug wires or ignition coils.
• Remove old spark plugs using a spark plug socket.
• Install new spark plugs with the proper gap according to manufacturer specifications (typically 0.028-0.032 inches).
• Reinstall ignition coils or spark plug wires.

3. Inspect and Replace Ignition Coils (if necessary)

• If misfire is traced back to a faulty ignition coil, remove the affected coil.
• Disconnect the wiring harness and unscrew the coil.
• Install the new ignition coil, ensuring it is seated properly and reconnect the wiring harness.

4. Check and Replace Fuel Injectors (if necessary)

• Use a noid light to check the fuel injector's electrical signal.
• If faulty, disconnect the fuel injector connector and remove the injector.
• Replace with a new injector and reconnect the electrical connector.

5. Address Vacuum Leaks

• Visually inspect vacuum hoses for cracks or disconnections.
• Replace any damaged hoses.
• Use a smoke test if necessary to identify hard-to-find leaks.