my BMW X5 F15 (2014-2019) has a check engine light P0171, what does it mean?

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before starting any work.

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, screwdrivers, vacuum gauge
• Inspect all hoses and connections in the air intake system for cracks or disconnections.
• Replace any damaged vacuum hoses and ensure all connections are tight.
• Reassemble the intake system and secure all clamps.

3. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Remove the fuel pressure test port cap.
• Connect the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
• Check the gauge reading; it should match the specifications provided in the repair manual.
• If the pressure is low, inspect the fuel pump and filter for issues.

4. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner (non-residue), Torx screwdriver
• Disconnect the MAF sensor connector.
• Remove the MAF sensor from its housing.
• Clean the sensor with MAF cleaner and allow it to dry completely.
• If the sensor is damaged, replace it with a new one.

5. Inspect Fuel Injectors

• Tools Required: Injector cleaning kit, multimeter
• Disconnect the fuel injector connectors.
• Use a multimeter to test the resistance of each injector; refer to the specifications.
• Clean the injectors using an injector cleaning kit if they are clogged, or replace them if necessary.