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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to prevent electrical issues.
• Allow the engine to cool down before beginning work.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Remove the engine cover (if applicable) to access the air intake.
  2. Visually inspect the intake hoses and connections for cracks or loose fittings.
  3. Replace any damaged hoses or clamps.
  4. Use a smoke test to locate any hidden vacuum leaks if necessary.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor electrical connector.
  2. Remove the MAF sensor from the air intake tube.
  3. Clean the sensor with MAF cleaner spray. Avoid touching the sensor element with tools or fingers.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel Pressure

• Sub-steps:
  1. Attach a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "ON" position without starting the engine and check the pressure reading.
  3. Start the engine and observe if the pressure remains within the manufacturer’s specifications (typically around 50-60 psi).
  4. If pressure is low, consider replacing the fuel filter or fuel pump.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail to access the injectors.
  2. Inspect each injector for signs of clogging or leaks.
  3. Clean the injectors using an ultrasonic cleaner or replace them if necessary.
  4. Reinstall the fuel rail and ensure all connections are secure.

6. Check for Exhaust Leaks

• Sub-steps:
  1. Inspect the exhaust manifold and pipes for cracks or loose connections.
  2. Use a spray bottle with soapy water to identify leaks when the engine is running.
  3. Repair or replace any damaged exhaust components.