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

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to detect any leaks.
  • Replace any damaged hoses or components.
• Tools Required: Smoke machine or carburetor cleaner, pliers.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Locate the MAF sensor in the air intake duct.
  • Disconnect the electrical connector and unscrew the sensor.
  • Clean the sensor using MAF sensor cleaner; if damaged, replace with a new unit.
  • Reinstall the sensor and reconnect the electrical connector.
• Tools Required: MAF sensor cleaner, screwdriver.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail.
  • Start the engine and check the pressure; it should match the manufacturer's specifications (typically between 50-60 psi for the Golf).
  • If the pressure is low, inspect the fuel pump and filter for clogs or failures, and replace as necessary.
• Tools Required: Fuel pressure gauge, wrench.

5. Inspect Oxygen Sensors

• Sub-steps:
  • Locate the upstream oxygen sensor and check its wiring for damage.
  • Use a multimeter to test the sensor's voltage output; it should fluctuate between 0.1 to 0.9 volts.
  • Replace the sensor if it is not operating correctly.
• Tools Required: Multimeter, oxygen sensor socket.