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 ensure safety during repairs.
• Allow the engine to cool down if it was recently running.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines and the intake manifold for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks by applying it around suspected areas and observing for changes in engine RPM.
  3. Replace any damaged hoses or gaskets identified during the inspection.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver set
• Sub-steps:
  1. Locate the MAF sensor, typically situated between the air filter and throttle body.
  2. Disconnect the electrical connector and remove the sensor from the intake duct.
  3. Spray MAF sensor cleaner onto the sensing element and allow it to dry completely.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Attach the fuel pressure gauge to the test port.
  3. Turn the ignition to the "ON" position (do not start the engine) to check the pressure reading.
  4. Compare the reading to the manufacturer's specifications (usually between 50-60 psi).
  5. If the pressure is low, investigate potential issues with the fuel pump or fuel filter.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the engine cover and access the fuel injectors.
  2. Check for any signs of fuel leaks around the injectors.
  3. Use a multimeter to test the resistance of each injector (should be between 12-16 ohms).
  4. If any injectors are faulty, remove and replace them with new ones.