why does my BMW 3 Series G20/G21 (2019-2024) check engine light stay on?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to ensure safety while working on electrical components.

2. Address Fault Codes

• Use the OBD-II scanner to read and document error codes.
• Research each code to determine the specific issue (e.g., P0171 for lean condition).

3. Inspect and Repair Components

• Gas Cap:

  • Remove and visually inspect the gas cap for cracks or worn seals.
  • Replace if damaged.

• Spark Plugs and Ignition Coils:

  • Remove engine cover if necessary using a socket set.
  • Disconnect ignition coils and remove spark plugs.
  • Inspect plugs for wear; replace if necessary (OEM recommended).
  • Reinstall new plugs and coils, ensuring proper torque (typically 15-20 Nm).

• Vacuum Leaks:

  • Inspect hoses for cracks or disconnections.
  • Replace any damaged hoses.

4. Clear Error Codes

• Reconnect the battery.
• Use the OBD-II scanner to clear any stored error codes.

5. Test Drive

• Take the vehicle for a short test drive to check if the check engine light remains off.