how to fix P0302 misfire code in my BMW 3 Series F30/F31 (2012-2019)?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the ignition coil from cylinder 2 by undoing the retaining bolts and gently pulling it out.
  2. Remove the spark plug using a spark plug socket and ratchet.
  3. Inspect the spark plug for wear or damage (look for carbon buildup, cracks, or fouling).
  4. If necessary, replace with a new spark plug that matches OEM specifications (typically BMW-approved NGK or Bosch).
  5. Torque the new spark plug to the manufacturer’s specifications (usually around 22 lb-ft).

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is fine, inspect the ignition coil on cylinder 2 for cracks or damage.
  2. If faulty, replace the ignition coil with a new OEM or high-quality aftermarket part.
  3. Reinstall the ignition coil, ensuring it seats properly and reconnect the electrical connector.

4. Inspect Fuel Injector

• Sub-steps:
  1. If the issue persists, check the fuel injector wiring and connector for damage.
  2. Use a multimeter to test the injector’s resistance; it should match manufacturer specifications.
  3. If the injector is faulty, replace it with a new one, ensuring it is properly seated and connected.

5. Verify and Reconnect

• Sub-steps:
  1. Reconnect the negative battery terminal and clear any fault codes using the OBD-II scanner.
  2. Start the engine and monitor for any check engine light reactivation.