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

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

• Sub-steps:

  1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  2. Use a smoke machine or propane torch to detect leaks around the intake manifold and vacuum lines.
  3. Replace any damaged hoses or gaskets found during inspection.

• Tools Required:

  • Smoke machine (or propane torch)
  • Hose clamp pliers

3. Check and Clean the MAF Sensor

• Sub-steps:

  1. Disconnect the MAF sensor electrical connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the MAF sensor with MAF cleaner spray (do not use other cleaning agents).
  4. Reinstall the MAF sensor and reconnect the electrical connector.

• Tools Required:

  • Screwdriver set
  • MAF cleaning spray

4. Test and Repair Fuel System

• Sub-steps:

  1. Connect the fuel pressure gauge to the fuel rail's test port.
  2. Turn the ignition key to the "ON" position (do not start the engine) and check the fuel pressure.
  3. Compare the reading with manufacturer specifications (usually around 50-60 psi for most models).
  4. If pressure is low, check the fuel pump relay, fuses, and wiring. Replace the fuel pump if necessary.

• Tools Required:

  • Fuel pressure gauge
  • Multimeter

5. Inspect PCV System

• Sub-steps:

  1. Locate the PCV valve and hoses connected to it.
  2. Remove the PCV valve and check for blockage or damage.
  3. Replace the PCV valve if it is clogged or malfunctioning.
  4. Inspect and replace any damaged PCV hoses.

• Tools Required:

  • Pliers
  • Replacement PCV valve and hoses