how to fix P0171 code in BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid any electrical shorts.
• Allow the engine to cool completely.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold and throttle body for cracks or disconnections.
  2. Use a smoke machine, if available, to identify any hidden leaks.
  3. Replace any damaged hoses or gaskets as needed.

3. Clean the MAF Sensor

• Tools Required:
  • MAF sensor cleaner
  • Torx screwdriver
• Sub-steps:
  1. Locate the MAF sensor on the air intake duct.
  2. Disconnect the electrical connector and remove the sensor by unscrewing it.
  3. Spray the MAF sensor with a dedicated cleaner and allow it to dry completely before reinstallation.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the 'ON' position without starting the engine and check the fuel pressure.
  3. Refer to the service manual for the correct pressure specifications.
  4. If the pressure is low, check the fuel pump and replace the fuel filter if necessary.

5. Inspect Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) oxygen sensor in the exhaust system.
  2. Disconnect the sensor and use a multimeter to check its resistance and voltage output. Refer to the service manual for specifications.
  3. Replace the oxygen sensor if it is not functioning within the specified parameters.