how to resolve P0171 code in BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before starting repairs.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, smoke machine (if available).
• Inspect all vacuum hoses and connections for damage or wear.
• Perform a smoke test to identify hidden leaks.
• Replace any damaged hoses or gaskets found during inspection.

3. Clean or Replace MAF Sensor

• Tools Required: Torx screwdriver, MAF cleaner.
• Remove the MAF sensor from the air intake duct.
• Spray the MAF sensor with MAF cleaner and let it dry completely.
• Reinstall the MAF sensor ensuring all connections are secure.

4. Check Fuel System

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the ON position (do not start the engine) to check fuel pressure.
• If the pressure is below specifications, check the fuel pump and replace the fuel filter if clogged.
• Replace the fuel pump if necessary.

5. Inspect and Test Fuel Injectors

• Tools Required: Multimeter, injector cleaning kit.
• Check the resistance of each injector with a multimeter; replace any that are out of specification.
• Perform a fuel injector cleaning if they are clogged.

6. Clean Throttle Body

• Tools Required: Throttle body cleaner, cleaning brush.
• Remove the throttle body from the intake manifold.
• Clean the throttle body with throttle body cleaner and a brush.
• Reinstall the throttle body ensuring a proper seal.