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

Solution

1. Preparation

• Gather tools and parts. Ensure the vehicle is parked on a level surface and the engine is cool.
• Tools Required: Socket set, torque wrench, multimeter, spark plug socket, compression tester, fuel injector cleaning kit.

2. Spark Plug Replacement

• Sub-steps:
  1. Remove the engine cover (if applicable) using a socket set.
  2. Disconnect the ignition coil connector for cylinder 1.
  3. Remove the ignition coil from cylinder 1 using a socket wrench.
  4. Remove the spark plug using a spark plug socket. Inspect for signs of wear or fouling.
  5. Install a new spark plug, ensuring it is the correct type and gap specification (typically 0.028-0.032 inches for BMW).
  6. Reinstall the ignition coil and reconnect the connector.

3. Ignition Coil Testing/Replacement

• Sub-steps:
  1. If the misfire follows after swapping coils, replace the ignition coil for cylinder 1.
  2. Ensure the new coil is seated properly and reconnect the electrical connector.

4. Fuel Injector Cleaning/Replacement

• Sub-steps:
  1. If the injector is suspected to be faulty, remove the fuel rail to access the injector.
  2. Disconnect the fuel line carefully and relieve fuel pressure.
  3. Remove the fuel injector from cylinder 1 and inspect for clogs.
  4. Clean the injector using a fuel injector cleaning kit or replace it with a new one.
  5. Reassemble the fuel rail and reconnect lines, ensuring all seals are intact.

5. Compression Test

• Sub-steps:
  1. Remove the spark plug for cylinder 1 to gain access for the compression tester.
  2. Insert the compression tester and crank the engine for a few seconds.
  3. Record the compression reading and compare it to manufacturer specifications (typically around 140-200 psi).
  4. If compression is low, further diagnostics may be required to check for valve issues or head gasket failure.