how to diagnose P0171 code in Volkswagen Golf Eighth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety during electrical component inspection.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses and connections for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to identify leaks around the intake manifold and throttle body area.
  3. Replace any damaged hoses or gaskets found during inspection.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Carefully disconnect the electrical connector from the MAF sensor.
  3. Remove the MAF sensor using a Torx or Phillips screwdriver.
  4. Clean the sensor wires with MAF cleaner; do not touch the wires directly.
  5. If cleaning does not resolve the issue, replace the MAF sensor with a new unit.

4. Fuel System Inspection

• Sub-steps:
  1. Check fuel pressure using a fuel pressure gauge; it should match the manufacturer specifications (typically around 58-62 psi).
  2. If pressure is low, inspect the fuel pump and fuel filter, replacing as necessary.
  3. Inspect fuel injectors for function by checking for clogs and ensuring they are properly connected.

5. Oxygen Sensor Testing

• Sub-steps:
  1. Locate the upstream oxygen sensor (before the catalytic converter).
  2. Use a multimeter to check the O2 sensor voltage signal; it should fluctuate between 0.1V to 0.9V.
  3. Replace the O2 sensor if it is not functioning properly.