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

Solution

1. Preparation

• Tools Required: OBD-II scanner, vacuum gauge, fuel pressure gauge, multimeter, basic hand tools (sockets, wrenches).
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues.

2. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses and intake manifold gaskets for cracks or disconnections.
  2. Use a vacuum gauge to check for abnormal readings at the intake manifold.
  3. If a leak is found, replace the affected hose or gasket.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the MAF sensor.
  3. Clean the MAF sensor with MAF cleaner spray; avoid touching the sensor element.
  4. If the sensor is damaged or heavily contaminated, replace it with a new one.

4. Verify Fuel Pressure

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail's service port.
  2. Turn the ignition to the "ON" position without starting the engine and check the pressure reading.
  3. It should meet manufacturer specifications (typically around 50-60 psi for most VW models). If low, inspect the fuel pump and filter.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Access the fuel injectors by removing the engine cover if necessary.
  2. Check for any visible cracks or leaks at the injector seals.
  3. Use a multimeter to test for proper resistance; replace any faulty injectors.

6. Replace Oxygen Sensor (if necessary)

• Sub-steps:
  1. Locate the upstream oxygen sensor (usually before the catalytic converter).
  2. Disconnect the electrical connector and unscrew the sensor using an oxygen sensor socket.
  3. Install the new sensor, making sure to use anti-seize compound on the threads.
  4. Reconnect the electrical connector.