how to troubleshoot P0171 code on Volkswagen Passat B8 (2015-2022)?

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the vehicle is on a flat surface and securely support it if needed.

2. Inspect and Repair Air Intake System

• Tools Required: Screwdriver set, vacuum gauge, smoke machine.
• Check all intake hoses for cracks or disconnections.
  • Tighten loose clamps and replace damaged hoses.
• Use a smoke machine to identify any vacuum leaks in the intake manifold.
  • Repair or replace gaskets and seals as necessary.

3. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner spray, Torx screwdriver.
• Remove the MAF sensor from the intake tract.
• Spray with MAF cleaner and allow to dry completely before reinstalling.
• If cleaning does not resolve issues, replace the MAF sensor with a new one.

4. Test and Repair Fuel System

• Tools Required: Fuel pressure gauge, socket set.
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "On" position (do not start) and check the pressure.
  • Compare the reading to the manufacturer's specifications.
• If pressure is low, check the fuel pump and filter, replacing as necessary.

5. Inspect and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit, socket set.
• Remove the fuel injectors from the rail.
• Use a fuel injector cleaning kit to clean or replace any faulty injectors.
• Reinstall injectors ensuring they are seated properly.