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

Solution

1. Preparation

• Gather tools and parts: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge.
• Ensure the vehicle is parked on a level surface and the engine is turned off.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plugs

1. Remove engine cover (if applicable) using a socket set.
2. Disconnect ignition coil connectors.
3. Unscrew and remove ignition coils using a socket wrench.
4. Remove spark plugs using a spark plug socket.
5. Inspect spark plugs for signs of wear or carbon buildup. Replace if necessary.
6. Install new spark plugs, ensuring the torque specification is met (typically 18-22 lb-ft).
7. Reinstall ignition coils securely and reconnect electrical connectors.

3. Check and Replace Ignition Coils

1. Use a multimeter to test each ignition coil for proper resistance (consult specifications for your model).
2. Replace any faulty ignition coils with new ones.
3. Reconnect all ignition coil connectors and ensure they are secure.

4. Fuel System Inspection

1. Connect a fuel pressure gauge to the fuel rail.
2. Turn the ignition to the "ON" position (do not start the engine) and check fuel pressure against manufacturer specifications.
3. If pressure is low, inspect fuel injectors for clogs; clean or replace as needed.
4. Check fuel pump operation and replace if defective.

5. Vacuum Leak Inspection

1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
2. Use a smoke machine or carburetor cleaner to identify leaks by observing engine RPM changes.
3. Replace any damaged hoses.