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

Solution

1. Preparation

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

2. Inspect and Clean MAF Sensor

• Remove the MAF sensor from the intake duct.
• Use MAF sensor cleaner to spray the sensor elements (do not touch the elements directly).
• Allow the sensor to dry completely before reinstalling it.

3. Check and Repair Vacuum Leaks

• Visually inspect all vacuum hoses for cracks or disconnections.
• Replace any damaged hoses with new ones.
• Use a smoke machine or propane to detect leaks if necessary.

4. Inspect Air Intake System

• Check the air filter for clogs and replace it if necessary.
• Ensure all connections from the air filter to the throttle body are secure and leak-free.
• Replace any damaged components in the intake system.

5. Test Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine and check pressure; it should be within manufacturer specifications.
• If pressure is low, inspect the fuel pump and filter for issues and replace if necessary.

6. Reconnect Battery and Clear Codes

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0171 code from the ECM.