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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, fuel pressure gauge, torque wrench
• Ensure the engine is cool. Disconnect the negative battery cable to prevent electrical shorts.

2. Replace Spark Plugs

1. Remove the engine cover if applicable.
2. Remove the ignition coil bolts and disconnect the electrical connectors.
3. Carefully pull the ignition coils out.
4. Use a spark plug socket to remove the spark plugs.
5. Inspect the spark plugs for damage or wear; replace with OEM plugs if necessary.
6. Install new spark plugs and torque them to the manufacturer's specifications.

3. Inspect and Replace Ignition Coils (if necessary)

1. Check the condition of the ignition coils visually and electrically.
2. If faulty, remove the ignition coils as described in the spark plug section.
3. Install new ignition coils, ensuring they are seated properly.
4. Reconnect the electrical connectors and secure with bolts.

4. Check Fuel Injectors

1. Remove the fuel rail if injectors are suspected to be faulty.
2. Inspect injectors for clogs and function; use a fuel injector cleaner if necessary.
3. Replace any defective injectors with OEM parts.
4. Reinstall the fuel rail and ensure all connections are secure.

5. Inspect Vacuum Lines and Intake Manifold

1. Visually inspect all vacuum lines for cracks or disconnections.
2. Replace any damaged vacuum hoses.
3. Check the intake manifold gaskets for leaks and replace if necessary.

6. Verify Fuel Pressure

1. Connect a fuel pressure gauge to the fuel rail.
2. Turn the ignition to the "On" position (do not start) and check the pressure against manufacturer specifications.
3. If the pressure is low, inspect the fuel pump and filter for blockages or failure.