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

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

• Inspect all vacuum lines and the intake manifold for cracks or breaks.
• Replace any damaged hoses or gaskets.
• Use a smoke machine to detect any hidden leaks if necessary.

3. Check Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine and check the pressure reading.
  • Ensure it meets the specification (typically around 50-60 PSI for a Golf MK7.5).
• If pressure is low, inspect the fuel pump and fuel filter for issues and replace if necessary.

4. Clean or Replace the MAF Sensor

• Locate the MAF sensor in the air intake path.
• Disconnect the electrical connector and remove the sensor.
• Use MAF sensor cleaner to clean the sensor elements.
• Reinstall the sensor securely and reconnect the electrical connector.

5. Inspect and Test the ECT Sensor

• Locate the ECT sensor on the engine.
• Check the wiring for any signs of wear or damage.
• Use a multimeter to test the resistance of the sensor and compare it to manufacturer specifications.
• Replace the sensor if it is out of specification.

6. Clear the Code and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the stored P0171 code.
• Perform a test drive to ensure the issue is resolved and monitor fuel trim data.