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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the vehicle to cool if the engine has been running.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, zip ties.
• Sub-steps:
  1. Visually inspect all vacuum hoses and connections for cracks or disconnections.
  2. Use a vacuum gauge to check for leaks; a low reading indicates a potential leak.
  3. Replace any damaged hoses or tighten loose connections.

3. Fuel System Inspection

• Tools Required: Fuel pressure gauge, socket set.
• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Attach the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
  3. Check the fuel pressure reading against manufacturer specifications; typically, it should be between 50-60 psi.
  4. If pressure is low, check the fuel pump operation and replace if necessary.

4. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner, screwdriver.
• Sub-steps:
  1. Disconnect the MAF sensor electrical connector.
  2. Remove the MAF sensor from the intake system.
  3. Clean the sensor wire or element with MAF cleaner and allow it to dry.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

5. Check Fuel Injectors

• Tools Required: Multimeter, fuel injector cleaning kit.
• Sub-steps:
  1. Disconnect the fuel injector connectors.
  2. Check each injector's resistance with a multimeter; it should typically be between 12-16 ohms.
  3. If any injectors are faulty, replace them. Otherwise, clean the injectors with a fuel injector cleaning kit.

6. Oxygen Sensor Inspection

• Tools Required: O2 sensor socket, multimeter.
• Sub-steps:
  1. Inspect the oxygen sensor wiring for any damage.
  2. Use a multimeter to check the sensor voltage output while the engine is running (should fluctuate between 0.1 to 0.9 volts).
  3. Replace the oxygen sensor if it is not functioning properly.