how to diagnose P0171 code in Volkswagen Golf MK7.5 (2020-Present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the negative battery terminal for safety.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Use a smoke machine to detect any vacuum leaks in the intake system.
  2. Replace any damaged vacuum hoses or seals found during inspection.
  3. Reconnect any disconnected hoses securely.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Remove the MAF sensor from the intake duct by unscrewing the mounting screws.
  2. Clean the MAF sensor using MAF cleaner spray; ensure not to touch the sensor elements.
  3. If the sensor is damaged, replace it with a new one.
  4. Reinstall the MAF sensor and ensure all connections are tight.

4. Verify Fuel Pressure

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition on (do not start the engine) and check the pressure reading.
  3. Compare the reading to the manufacturer's specifications; replace the fuel pump if pressure is low.

5. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0171 code.
  3. Take the vehicle for a test drive, monitoring engine performance for any reoccurrence of the code.