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

Solution

1. Preparation

• Tools Needed: OBD-II scanner, socket set, screwdrivers, fuel pressure gauge, MAF cleaner, vacuum gauge.
• Safety Warning: Disconnect the battery before starting any electrical work.

2. Inspect and Repair Air Intake System

1. Visually inspect the air intake duct, including the connections to the throttle body and MAF sensor.
2. Secure any loose connections and replace any damaged hoses.
3. If any cracks are found in the intake duct, replace the entire duct assembly.

3. Clean or Replace MAF Sensor

1. Remove the MAF sensor from the air intake duct.
2. Use MAF sensor cleaner to spray the sensor elements. Allow to dry completely before reinstalling.
3. If cleaning does not resolve the issue, replace the MAF sensor with a new one.

4. Check Fuel Pressure

1. Connect the fuel pressure gauge to the fuel rail test port.
2. Turn the ignition to the "ON" position (do not start the engine) and record the pressure reading.
3. If the pressure is below specifications (typically around 50-60 psi for most BMWs), inspect the fuel pump and filter for replacements.

5. Inspect Intake Manifold and Vacuum Hoses

1. Remove the intake manifold if necessary to check the gaskets for leaks.
2. Replace any worn or damaged gaskets.
3. Inspect all vacuum hoses connected to the manifold and replace any that are cracked or disconnected.