how to fix P0301 misfire code in BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, fuel injector cleaner.
• Disconnect the vehicle's battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coil wiring harness from the ignition coil at cylinder 1.
  3. Remove the ignition coil using a socket wrench.
  4. Extract the spark plug using a spark plug socket.
  5. Inspect the spark plug for wear, carbon deposits, or oil fouling. Replace if necessary.
  6. Gap the new spark plug according to manufacturer specifications.
  7. Install the new spark plug and torque it to the manufacturer’s specification (usually around 22 Nm).
  8. Reinstall the ignition coil and reconnect the wiring harness.

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is in good condition, test the ignition coil using a multimeter (check primary and secondary resistance).
  2. If the coil is faulty, remove it and replace it with a new ignition coil.
  3. Reinstall the ignition coil and reconnect the wiring harness.

4. Check and Clean Fuel Injector

• Sub-steps:
  1. If initial components are verified, check the fuel injector operation by using a multimeter to test the injector's resistance.
  2. If the injector is faulty, disconnect the fuel line and electrical connector.
  3. Remove the fuel injector from the rail.
  4. Clean or replace the injector as necessary.
  5. Reinstall the injector, making sure to use new O-rings if replaced.

5. Perform Compression Test (if needed)

• Sub-steps:
  1. Remove the spark plug from cylinder 1.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine and record the compression reading.
  4. Compare the reading with specifications; if low, further diagnostics are necessary.
  5. Reinstall the spark plug if no issues are found.