why does my BMW 3 Series F30/F31 (2012-2019) check engine light keep coming on

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety while working on electrical systems.

2. Addressing Error Codes

• Sub-step 1: Based on the OBD-II scanner results, identify the specific fault codes (e.g., P0300 for misfire, P0420 for catalytic efficiency).
• Sub-step 2: Research the codes to understand the potential causes and affected components.

3. Replace Faulty Components

• Sub-step 1: If spark plugs or ignition coils are identified as faulty, remove the engine cover (if applicable) using a socket set.
• Sub-step 2: Replace the spark plugs with OEM or high-quality aftermarket alternatives, ensuring proper torque (typically around 16 ft-lbs).
• Sub-step 3: If ignition coils are faulty, disconnect the electrical connectors and remove them; replace with new coils.

4. Check Fuel System

• Sub-step 1: If fuel trim issues are present, inspect the fuel injectors for clogging; use a fuel injector cleaner if necessary.
• Sub-step 2: Replace any faulty fuel injectors, ensuring to use new O-rings during installation for proper sealing.

5. Inspect and Replace Other Components

• Sub-step 1: If vacuum leaks are suspected, inspect and replace any damaged vacuum hoses.
• Sub-step 2: If the catalytic converter is found to be faulty, consult the service manual for removal and installation procedures, and replace with OEM parts.