how can I fix the check engine light on my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Disconnect the vehicle's negative battery terminal to prevent electrical shock.

2. Addressing Specific Error Codes

• 2.1. Fixing a P0420 Code (Catalytic Converter Efficiency Below Threshold)

  • Inspect the exhaust system for leaks.
  • Replace faulty oxygen sensors if indicated.
  • If the catalytic converter is damaged, replace it following these steps:
    • Raise the vehicle and secure it on jack stands.
    • Remove the exhaust pipe bolts using a socket set.
    • Replace the old catalytic converter with a new one.
    • Reinstall the exhaust pipe and tighten bolts to manufacturer specifications (consult repair manual for torque values).

• 2.2. Fixing a P0300 Code (Random Misfire Detected)

  • Check and replace faulty spark plugs or ignition coils.
  • Remove the ignition coil using a socket wrench.
  • Replace with new coils and ensure they are seated correctly.
  • Reinstall the spark plug and tighten to the specified torque.

• 2.3. Fixing a P0171 Code (System Too Lean)

  • Inspect the MAF sensor for dirt and clean it using MAF cleaner.
  • Check vacuum hoses for leaks and replace any damaged ones.
  • If necessary, replace the fuel filter and check fuel pressure.

3. Clear Error Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the error codes from the system.