how to fix the P0171 code on my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety.
• Allow the engine to cool down before starting work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Socket set, screwdrivers, vacuum gauge
• Inspect all vacuum hoses and the intake manifold for cracks or loose connections.
• If leaks are found, replace the damaged hoses or reseal the intake manifold.
• Use a vacuum gauge to verify that the system holds vacuum after repairs.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF cleaner, Torx screwdriver
• Remove the MAF sensor from the intake duct.
• Use MAF cleaner to gently clean the sensor elements. Avoid touching them directly.
• Reinstall the MAF sensor and ensure all connections are secure.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading.
• If the pressure is below specifications, check the fuel pump and filter for issues and replace as necessary.

5. Inspect Fuel Injectors

• Tools Required: Injector cleaner, socket set
• Remove the fuel injectors from the fuel rail.
• Clean the injectors using an appropriate injector cleaner or replace them if they are clogged or leaking.
• Reinstall the injectors and ensure they are secured properly.

6. Replace Engine Coolant Temperature Sensor (if faulty)

• Tools Required: Socket set, coolant
• Locate the engine coolant temperature sensor on the engine block.
• Disconnect the electrical connector and remove the sensor.
• Install the new sensor and reconnect the electrical connector.
• Refill the coolant if necessary and check for leaks.