how to fix P0300 random misfire code on my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather all necessary tools and parts. Ensure the vehicle is parked on a flat surface and the engine is cool.
• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge, vacuum gauge.

2. Spark Plug Replacement

• Remove the engine cover if applicable.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Using a socket wrench, remove the spark plug wires or ignition coil connectors.
• Unscrew and remove the spark plugs using a spark plug socket.
• Inspect the spark plugs for wear; replace with OEM or high-quality aftermarket plugs at the specified gap.
• Reinstall the new spark plugs and reconnect the ignition coils or wires.

3. Ignition Coil Inspection/Replacement

• If the spark plugs are in good condition, test the ignition coils with a multimeter for resistance, comparing to manufacturer specifications.
• Replace any faulty ignition coils.
• Reconnect the ignition coils and ensure they are seated properly.

4. Fuel System Inspection

• Connect a fuel pressure gauge to the fuel rail and turn on the ignition to check fuel pressure against manufacturer specifications.
• If pressure is low, inspect the fuel pump and fuel filter for blockages or failure. Replace if necessary.
• Clean or replace fuel injectors if they are clogged.

5. Air Intake Inspection

• Inspect the air filter for dirt and debris; replace if necessary.
• Check the intake manifold for vacuum leaks using a vacuum gauge or by spraying carburetor cleaner around the gaskets and hoses while the engine is running.
• Tighten or replace any loose connections or damaged hoses.