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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before beginning work.

2. Inspect Air Intake System

• Tools Required: Visual inspection tools, flashlight.
• Sub-steps:
  1. Visually inspect the air intake hoses for cracks or loose connections.
  2. Listen for hissing sounds that indicate vacuum leaks.
  3. Replace any damaged hoses or clamps.

3. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner, small screwdriver.
• 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, ensuring not to touch the sensor element.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Sub-steps:
  1. Locate the fuel rail and connect the fuel pressure gauge to the service port.
  2. Turn the ignition on (do not start) and observe the fuel pressure reading.
  3. Compare the reading to the manufacturer's specifications (typically around 50-60 psi).
  4. If pressure is low, inspect fuel pump and fuel filter for issues.

5. Inspect Oxygen Sensor

• Tools Required: Multimeter, socket set.
• Sub-steps:
  1. Locate the upstream oxygen sensor.
  2. Disconnect the sensor and test its resistance with a multimeter.
  3. Inspect the wiring for damage or corrosion.
  4. Replace the sensor if readings are outside manufacturer specifications.

6. Reassemble and Reset ECU

• After all inspections and repairs, reconnect any components removed.
• Reconnect the battery terminal.
• Use an OBD-II scanner to clear the P0171 code and reset the ECU.