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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to ensure safety.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  2. Use a smoke machine to detect any hidden leaks in the intake system.
  3. Replace any damaged hoses or gaskets found during inspection.

3. Clean MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor from the intake.
  3. Use MAF cleaner to spray the sensor elements; avoid touching them with fingers.
  4. Allow the sensor to dry before reinstalling.

4. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition key to the "ON" position without starting the engine to check the fuel pressure.
  3. Compare the reading to the manufacturer's specifications (typically around 50-60 psi for most gasoline engines).
  4. If the pressure is low, inspect the fuel pump and fuel filter for issues.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail with the injectors still attached.
  2. Check for any visible clogs or signs of wear on the injectors.
  3. Use a fuel injector cleaning kit to clean the injectors if necessary.
  4. Reinstall the injectors and fuel rail, ensuring proper sealing.

6. Replace Oxygen Sensor (if necessary)

• Sub-steps:
  1. Locate the upstream oxygen sensor (pre-catalytic converter).
  2. Disconnect the electrical connector and unscrew the sensor using an O2 sensor socket.
  3. Install the new oxygen sensor and reconnect the electrical connector.