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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Disconnect the battery to avoid electrical shorts during the repair process.
• Allow the engine to cool down before starting work.

2. Spark Plug and Ignition Coil Inspection

• Remove the engine cover (if necessary) to access the spark plugs and ignition coils.
• Using a socket set, carefully remove the spark plugs from each cylinder.
• Inspect each spark plug for wear and carbon buildup; replace any damaged plugs.
• Remove the ignition coils by disconnecting the electrical connectors and unscrewing them from the cylinder head.
• Inspect the ignition coil terminals for corrosion and replace faulty coils.

3. Fuel Injector Inspection

• Check the fuel rail for accessibility; disconnect the fuel line (using a line wrench) and relieve fuel pressure.
• Remove the fuel injectors by unscrewing them from the fuel rail.
• Inspect each injector for clogs or leaks; clean or replace as necessary.

4. Vacuum Leak Check

• Inspect all vacuum lines for cracks or disconnections; replace any damaged hoses.
• Use a smoke machine or carburetor cleaner to locate any potential vacuum leaks.

5. Fuel Pressure Test

• Reconnect the fuel line and attach a fuel pressure gauge to the test port on the fuel rail.
• Start the engine and observe the gauge reading; it should be within the manufacturer’s specified range.
• If the pressure is low, consider replacing the fuel filter or fuel pump.