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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the vehicle is on a flat surface and secure it with wheel chocks.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, flashlight
• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a vacuum gauge to test for leaks; a reading lower than normal indicates a leak.
  3. Replace any damaged hoses and recheck for leaks.

3. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner (non-residue type), screwdriver
• Sub-steps:
  1. Disconnect the wiring harness from the MAF sensor.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the sensor wires gently with MAF cleaner. If damaged, replace the sensor with a new one.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Locate the fuel rail and connect the fuel pressure gauge to the test port.
  2. Turn the ignition to the "ON" position without starting the engine to check the pressure reading.
  3. If the pressure is below specifications, check the fuel pump and filter for issues.

5. Inspect and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit (optional), socket set
• Sub-steps:
  1. Remove the fuel injectors from the fuel rail.
  2. Use a cleaning kit or solvent to clean the injector nozzles.
  3. Reinstall the injectors and ensure they are seated correctly; replace any O-rings if necessary.