my BMW 5 Series G30/G31 (2017-2024) has a P0171 code, what are the common causes?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Repair Vacuum Lines

• Sub-steps:
  • Visually inspect all vacuum hoses connected to the intake manifold.
  • Use a smoke machine to detect any leaks if visual inspection does not reveal obvious issues.
  • Replace any damaged or cracked vacuum hoses.
• Tools Required: Smoke machine, basic hand tools.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Disconnect the MAF sensor electrical connector.
  • Remove the MAF sensor from the intake manifold.
  • If cleaning, use MAF cleaner spray to clean the sensor elements; if replacing, install a new sensor.
  • Reinstall the MAF sensor and reconnect the electrical connector.
• Tools Required: Torx or socket set, MAF cleaner spray (if cleaning).

4. Inspect and Repair Fuel Delivery System

• Sub-steps:
  • Check the fuel pump operation by listening for a humming sound when the ignition is turned on.
  • Inspect the fuel filter for clogs; replace if necessary.
  • Use a fuel pressure gauge to check for proper fuel pressure at the fuel rail.
  • If fuel injectors are suspected, consider cleaning or replacing them.
• Tools Required: Fuel pressure gauge, basic hand tools.

5. Inspect Intake Manifold

• Sub-steps:
  • Remove any components obstructing access to the intake manifold.
  • Check the manifold gasket for wear or damage and replace if necessary.
  • Ensure the manifold is properly seated and all bolts are torqued to specifications.
• Tools Required: Socket set, torque wrench.