my BMW 3 Series F30/F31 (2012-2019) check engine light comes on and off

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical shorts while working on the vehicle.
• Allow the engine to cool before starting work.

2. Code Diagnosis and Clearing

• Connect the OBD-II scanner to the vehicle's diagnostic port.
• Retrieve and document trouble codes.
• Clear the codes and take the vehicle for a test drive to see if the check engine light reappears.

3. Inspect and Repair Fuel System

• Tools Required: Fuel pressure gauge, socket set.
• Check fuel pressure using the gauge; compare readings to specifications.
• If pressure is low, inspect the fuel pump and filter; replace if necessary.
• Inspect fuel injectors for clogs or leaks; clean or replace as needed.

4. Check and Replace Ignition Components

• Tools Required: Socket set, torque wrench.
• Remove engine cover, if applicable.
• Inspect spark plugs; replace if worn or fouled, ensuring to use manufacturer specifications for gap size.
• Check ignition coils for proper operation; replace any faulty coils.

5. Evaluate Air Intake System

• Tools Required: Screwdriver set, cleaning supplies.
• Remove the air filter; inspect for dirt and blockages, replacing if necessary.
• Clean the throttle body with appropriate cleaner to remove carbon build-up.
• Ensure the intake manifold is securely fastened and free from leaks.

6. Inspect Exhaust System

• Tools Required: Jack and jack stands, socket set.
• Raise the vehicle and inspect the exhaust system for any visible damage or leaks.
• Repair or replace damaged sections of exhaust piping or gaskets.