what does it mean when my BMW X3 F25 (2011-2018) shows a P0171 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during the repair.
• Allow the engine to cool before starting work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, screwdriver set, flashlight
• Visually inspect all vacuum hoses and connections for cracks or disconnections.
• Use a vacuum gauge to test the intake manifold for leaks.
• Replace any damaged hoses or seals.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver set
• Disconnect the MAF sensor electrical connector.
• Remove the MAF sensor from the air intake duct.
• Spray the MAF sensor with MAF cleaner and allow it to dry.
• Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel System

• Tools Required: Fuel pressure gauge, socket set
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "On" position (do not start) and check the fuel pressure reading against manufacturer specifications.
• If pressure is low, inspect the fuel pump and filter for blockage or failure. Replace the fuel filter if necessary.

5. Inspect Oxygen Sensors

• Tools Required: O2 sensor socket, multimeter
• Locate the upstream (pre-catalytic) oxygen sensor.
• Use an O2 sensor socket to remove the sensor.
• Test the sensor with a multimeter to ensure it operates within specifications. Replace if faulty.