my BMW 5 Series G30/G31 (2017-2024) has a check engine light and misfires how to diagnose

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the engine is cool before starting.
• Disconnect the battery to avoid electrical shorts.

2. Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover (if applicable) by unscrewing any retaining bolts.
  2. Disconnect ignition coil connectors by pressing down on the tab.
  3. Unscrew ignition coils and carefully remove them from the spark plug wells.
  4. Use a spark plug socket to remove old spark plugs.
  5. Install new spark plugs, tightening them to the manufacturer's torque specification (typically around 22 lb-ft).
  6. Reinstall ignition coils and reconnect their connectors.

3. Test and Replace Ignition Coils (if necessary)

• Sub-steps:
  1. If misfires persist, test each ignition coil using a multimeter.
  2. Replace faulty ignition coils with new ones, ensuring they match OEM specifications.
  3. Reconnect all connectors securely.

4. Check and Replace Fuel Injectors (if necessary)

• Sub-steps:
  1. Remove the fuel rail assembly by unscrewing the retaining bolts and disconnecting fuel lines (use caution to avoid fuel spray).
  2. Remove injectors from the fuel rail and inspect for clogs or damage.
  3. Replace any faulty injectors with OEM parts.
  4. Reassemble the fuel rail and reconnect the fuel lines securely.

5. Clear Error Codes

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear any existing error codes.
  3. Start the engine and ensure the check engine light does not reappear.