how to fix P0171 code in Volkswagen Golf MK7 (2015-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is on a flat surface and safely secured.
• Disconnect the battery to prevent electrical shocks.

2. Inspect and Repair Air Intake System

• Inspect for Leaks:
  • Check all intake hoses and clamps visually for cracks or damage.
  • Use a smoke machine or carburetor cleaner around joints to detect leaks.
• Repair or Replace:
  • Replace any damaged hoses or clamps identified during inspection.

3. Fuel System Check

• Check Fuel Pressure:
  • Connect the fuel pressure gauge to the fuel rail.
  • Turn the ignition to the "On" position without starting the engine and record the pressure.
  • Compare with manufacturer specifications (typically around 50-60 psi for the Golf MK7).
• Replace Fuel Filter or Pump (if necessary):
  • If pressure is low, replace the fuel filter or fuel pump as required.

4. MAF Sensor Inspection

• Remove MAF Sensor:
  • Disconnect the electrical connector.
  • Unscrew the MAF sensor from the air intake duct.
• Clean MAF Sensor:
  • Use MAF cleaner spray to clean the sensor element.
  • Allow it to dry completely before reinstalling.

5. Inspect and Replace Vacuum Lines

• Visual Inspection:
  • Check all vacuum lines for cracks, wear, or disconnections.
• Replace Faulty Lines:
  • Replace any damaged vacuum lines with new ones.

6. Oxygen Sensor Testing

• Check Sensor Function:
  • Use a multimeter to test the voltage output of the upstream oxygen sensor.
  • Compare readings to specifications (typically should fluctuate between 0.1V and 0.9V).
• Replace Sensor (if faulty):
  • If the sensor is not functioning within specifications, replace it with a new one.