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

Solution

1. Preparation

• Gather tools and parts needed for repairs.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting any work.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses and gaskets for cracks or disconnections.
  2. Use a smoke machine or propane to detect leaks while the engine is running.
  3. Replace any damaged hoses or gaskets found.
• Tools Required: Smoke machine, propane torch (for testing), basic hand tools.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor from the intake tube.
  3. Clean the sensor using MAF cleaner spray. Do not touch the sensing element.
  4. If the sensor is faulty, replace it with a new one.
• Tools Required: Torx screwdriver, MAF cleaner spray.

4. Inspect Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition on (without starting the engine) to check pressure; compare with specifications.
  3. If pressure is low, inspect the fuel pump and replace the fuel filter if needed.
• Tools Required: Fuel pressure gauge, basic hand tools.

5. Test Oxygen Sensors

• Sub-steps:
  1. Use a multimeter to check the voltage output of the upstream oxygen sensor.
  2. If readings are outside the normal range (0.1 to 0.9 volts), consider replacing the sensor.
• Tools Required: Multimeter.

6. Clean Throttle Body

• Sub-steps:
  1. Remove the throttle body from the intake manifold.
  2. Use throttle body cleaner to clean any carbon deposits from the valve and housing.
  3. Reinstall the throttle body and reconnect all electrical connectors.
• Tools Required: Throttle body cleaner, socket set.