how to deal with P0171/P0174 lean condition codes on BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety during the repair process.
• Raise the vehicle if necessary for better access.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines and hoses for cracks or disconnections.
  2. Use a smoke machine or propane torch to detect leaks around the intake manifold and vacuum lines.
  3. Replace any damaged hoses or seals as needed.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor from the duct.
  3. Clean the MAF sensor with MAF cleaner spray; do not touch the sensor element.
  4. Reinstall the sensor and reconnect the electrical connector. If damaged, replace with a new sensor.

4. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition on (without starting the engine) to check for initial pressure; it should match the manufacturer's specifications.
  3. Start the engine and observe the pressure; it should remain stable under load.
  4. If pressure is low, check the fuel pump and fuel filter for replacement or repair.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Perform a visual inspection for any fuel leaks around the injectors.
  2. Use a multimeter to test the resistance of each injector; replace any that are out of specifications.
  3. If necessary, clean the injectors using a fuel injector cleaning kit.