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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, MAF sensor cleaner, fuel pressure gauge.
• Ensure the vehicle is parked on a level surface and the engine is off. Disconnect the battery before starting work on electrical systems.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect the intake hoses for cracks or loose fittings; replace any damaged components.
  2. Tighten all clamps and connections to ensure a secure fit.
  3. Check the air filter; replace if dirty or clogged.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector carefully.
  3. Remove the MAF sensor using the appropriate socket.
  4. Clean the sensor with MAF cleaner spray, ensuring no residue remains.
  5. Reinstall the sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail as per the manufacturer’s specifications.
  2. Start the engine and observe the fuel pressure reading; it should be within the specified range.
  3. If pressure is low, inspect the fuel pump, fuel filter, and fuel injectors for clogs or weaknesses.

5. Repair Vacuum Leaks

• Sub-steps:
  1. Inspect all vacuum lines for wear, cracks, or disconnections.
  2. Replace any damaged vacuum hoses.
  3. Use smoke testing if necessary to identify hard-to-find leaks.