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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the vehicle battery to prevent electrical shorts.
• Allow the engine to cool before starting work.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Compression tester
• Multimeter

2. Replace Spark Plugs

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connectors.
3. Unscrew and remove the ignition coils using a socket set.
4. Remove the old spark plugs using a spark plug socket.
5. Inspect the spark plug threads and clean if necessary.
6. Install new spark plugs, ensuring proper torque (typically 22 lb-ft).
7. Reinstall ignition coils and reconnect the connectors.

3. Test and Replace Ignition Coils (if necessary)

1. Using a multimeter, check the resistance of each ignition coil.
2. If the resistance is out of specification, replace the faulty coil(s).
3. Reinstall the new ignition coil(s) and ensure connections are secure.

4. Clean or Replace Fuel Injectors

1. If injectors are suspected to be clogged, remove them from the fuel rail.
2. Use a fuel injector cleaner to clean or replace them with new injectors.
3. Reinstall the fuel rail and ensure all connections are secure.

5. Inspect and Repair Vacuum Leaks

1. Visually inspect all vacuum lines connected to the intake manifold.
2. Replace any cracked or damaged hoses.
3. Use a smoke machine to detect any hidden leaks if necessary.

6. Clean MAF Sensor and Throttle Body

1. Disconnect the MAF sensor connector and remove the sensor from the intake.
2. Clean the MAF sensor with dedicated MAF cleaner.
3. Remove the throttle body and clean it with throttle body cleaner.
4. Reinstall both components after cleaning.