what does it mean if my Volkswagen Golf MK7 (2015-2019) is throwing a P0171 code?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks, splits, or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks around suspected areas.
  3. Replace any damaged hoses or gaskets as needed.

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 sensor from the housing.
  3. Clean the sensor using MAF cleaner; do not touch the sensor element.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Check Fuel Pressure

• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Connect a fuel pressure gauge to the test port.
  3. Turn the ignition to the 'ON' position without starting the engine and observe the pressure reading.
  4. Compare the reading with manufacturer's specifications (usually between 50-60 psi). If low, proceed to step 5.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the engine cover to access the fuel injectors.
  2. Disconnect the electrical connectors from the fuel injectors.
  3. Check for clogs or leaks by visually inspecting the injectors.
  4. Clean or replace any faulty injectors as necessary.

6. Verify O2 Sensor Operation

• Sub-steps:
  1. Using a multimeter, check the voltage output of the upstream O2 sensor.
  2. The voltage should fluctuate between 0.1 to 0.9 volts when the engine is running.
  3. Replace the O2 sensor if it does not meet these specifications.