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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses, intake manifold, and throttle body for cracks or disconnections.
  2. If any hoses are damaged, replace them with OEM parts.
  3. Use a smoke machine to detect hard-to-find leaks if necessary.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the wiring harness and remove the sensor.
  3. Clean the MAF sensor with MAF cleaner (do not touch the sensor element).
  4. If cleaning does not resolve the issue, replace the MAF sensor with a new one.

4. Inspect and Test 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. It should match the manufacturer's specifications.
  3. If the fuel pressure is low, inspect the fuel pump and filter for issues. Replace as necessary.
  4. Check each fuel injector for proper operation; replace any that are clogged or leaking.

5. Replace Engine Coolant Temperature Sensor (if faulty)

• Sub-steps:
  1. Locate the engine coolant temperature sensor, usually near the thermostat housing.
  2. Disconnect the electrical connector and remove the sensor using the appropriate socket.
  3. Install the new sensor, ensuring it is seated properly, and reconnect the wiring harness.