how to fix P0171 code in Volkswagen Passat B8 (2015-2022)

Solution

1. Preparation

• Tools Required: OBD-II scanner, vacuum gauge, fuel pressure gauge, MAF sensor cleaner, basic hand tools.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Use a vacuum gauge to check for leaks; a low reading indicates an issue.
  2. Visually inspect all vacuum hoses for cracks or disconnections.
  3. Replace any damaged hoses and tighten any loose connections.

3. Check and Clean MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector.
  3. Remove the MAF sensor using the appropriate socket.
  4. Spray MAF sensor cleaner on the sensing elements; do not touch them with your fingers.
  5. Reinstall the MAF sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  1. Locate the fuel rail and connect the fuel pressure gauge to the test port.
  2. Turn the ignition to the "ON" position without starting the engine and check the pressure reading; it should meet manufacturer's specifications (typically around 50-60 psi).
  3. If the pressure is low, check the fuel pump and filter for issues and replace as necessary.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Carefully remove the fuel rail with injectors attached.
  2. Inspect the injectors for clogging or leaks.
  3. Clean or replace the injectors as needed before reinstalling them.