my Volkswagen Golf MK6 (2009-2014) has a check engine light and code P0171, what's wrong?

Solution

1. Preparation

• Gather 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 Air Intake System

• Sub-steps:
  1. Visually inspect all air intake hoses for cracks or loose connections.
  2. Tighten any loose clamps or replace damaged hoses as necessary.
  3. If any hoses are damaged, replace them with OEM parts.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Remove the MAF sensor from the air intake duct.
  2. Clean the MAF sensor using a dedicated MAF cleaner, avoiding contact with the sensor elements.
  3. If cleaning does not resolve the issue, replace the MAF sensor with a new one.

4. Test and Repair Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the ON position but do not start the engine. Check the fuel pressure reading.
  3. If pressure is low, inspect the fuel pump, fuel filter, and fuel lines for blockages or failures.
  4. Replace any faulty components as necessary.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail to access the injectors.
  2. Inspect each injector for clogs or leaks.
  3. Clean the injectors using a professional injector cleaning kit or replace them if they are faulty.