how to fix P0301 misfire code in my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical issues.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench
• Remove the ignition coil cover if necessary.
• Disconnect the electrical connector from the ignition coil.
• Remove the ignition coil using a socket set.
• Inspect the spark plug for wear or damage, replacing it if necessary.
• Install the new spark plug using a torque wrench to the manufacturer's specified torque (usually around 18 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test and Replace Ignition Coil

• If the spark plug is in good condition but the misfire persists, test the ignition coil.
• Swap the ignition coil with another cylinder and check for a change in misfire code (e.g., if the code changes to P0302, the coil is faulty).
• Replace the ignition coil if it’s faulty, following the same steps as for the spark plug installation.

4. Inspect Fuel Injector

• Tools Required: Fuel injector testing kit
• Disconnect the fuel injector connector from cylinder 1.
• Use a multimeter to check the injector's resistance; compare it to specifications.
• If the injector is faulty, replace it by removing the fuel rail and installing a new injector.

5. Check for Vacuum Leaks

• Inspect all vacuum hoses and gaskets around the intake manifold and throttle body.
• Use a smoke machine or carburetor cleaner to identify leaks; repair or replace any damaged components.

6. Perform Compression Test

• Tools Required: Compression tester
• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine and record the compression reading; it should be within the manufacturer's specifications.
• If readings are low, further engine diagnostics may be necessary.