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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical issues.

2. Inspect and Repair Air Intake System

1. Visual Inspection
   • Check all intake hoses and gaskets for cracks or disconnections. Replace any damaged components.
2. Smoke Test for Leaks
   • Perform a smoke test to identify any hidden vacuum leaks. Repair any leaks found.

3. Check and Replace Fuel System Components

1. Fuel Pressure Test
   • Connect a fuel pressure gauge to the fuel rail.
   • Start the engine and check that the fuel pressure matches manufacturer specifications.
   • If the pressure is low, inspect and replace the fuel pump or fuel filter as necessary.
2. Replace Fuel Filter
   • If applicable, replace the fuel filter following manufacturer guidelines.

4. Clean or Replace MAF Sensor

1. Remove MAF Sensor
   • Disconnect the electrical connector and remove the MAF sensor from the air intake.
2. Clean Sensor
   • Use MAF cleaner spray to gently clean the sensor elements. Allow it to dry completely.
3. Reinstall MAF Sensor
   • Reinstall the sensor, ensuring the electrical connector is secure.

5. Inspect and Clean Throttle Body

1. Remove Throttle Body
   • Disconnect the air intake duct and electrical connectors. Remove the throttle body bolts and take it off.
2. Clean Throttle Body
   • Use throttle body cleaner and a soft cloth to remove carbon deposits. Ensure the throttle plate moves freely.
3. Reinstall Throttle Body
   • Reinstall the throttle body and reconnect all hoses and connectors securely.