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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 1 by unscrewing any retaining bolts and disconnecting the electrical connector.
• Unscrew the spark plug using a spark plug socket and ratchet.
• Inspect the old spark plug for wear; if it's fouled or damaged, replace it with a new one.
• Install the new spark plug, ensuring it is torqued to the manufacturer’s specifications (typically around 22 lb-ft).
• Reinstall the ignition coil, reconnecting the electrical connector and securing it with the bolts.

3. Replace Ignition Coil (if needed)

• If the ignition coil was found to be faulty, remove the old ignition coil from cylinder 1.
• Install the new ignition coil, ensuring it is seated properly and connected securely.
• Reconnect the electrical connector and ensure no wiring is pinched.

4. Test Fuel Injector

• If the injector is suspected to be faulty, remove the fuel rail to access the injector for cylinder 1.
• Disconnect the fuel line carefully, using a rag to catch any drips.
• Remove the fuel injector and test it with a multimeter (if applicable) or replace it with a new one.
• Reinstall the fuel injector in the fuel rail and reconnect the fuel line.

5. Perform Compression Test

• If misfire persists, perform a compression test on cylinder 1.
• Remove the spark plug and insert the compression tester into the spark plug hole.
• Crank the engine and read the compression value. Compare it to the manufacturer's specifications.
• If compression is low, further investigation into the engine internals may be necessary.