how to fix P0171 code in BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Hose clamps, vacuum gauge, smoke machine (if available)
• Check all vacuum hoses for cracks or disconnections. Replace any damaged hoses.
• Use a smoke machine to identify any hidden vacuum leaks around the intake manifold and gaskets.
• Tighten or replace intake manifold gaskets if leaks are detected.

3. Clean MAF Sensor

• Tools Required: MAF sensor cleaner or isopropyl alcohol, soft cloth
• Locate the MAF sensor in the intake duct.
• Carefully remove the sensor from its housing.
• Spray the MAF sensor with cleaner and allow it to dry completely before reinstalling.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Locate the Schrader valve on the fuel rail.
• Attach the fuel pressure gauge and turn the ignition to the ON position (without starting the engine) to check fuel pressure.
• Compare the reading to the manufacturer's specifications. If pressure is low, check the fuel pump and filter.

5. Inspect and Clean Fuel Injectors

• Tools Required: Fuel injector cleaner, injector cleaning kit (if necessary)
• Remove fuel injectors from the engine.
• Use a fuel injector cleaning kit to clean the injectors or replace them if they are clogged.
• Reinstall the injectors and ensure proper seating and sealing.

6. Check the Throttle Body

• Tools Required: Throttle body cleaner, soft brush
• Remove the air intake duct to access the throttle body.
• Clean any carbon buildup from the throttle body with throttle body cleaner and a soft brush.
• Reassemble the intake duct securely.