how to fix P0171 and P0174 codes on my Volkswagen Tiguan First Generation (2007-2018)?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative terminal of the battery to prevent electrical shorts.
• Ensure the engine is cool before beginning work.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Visually inspect all hoses connected to the air intake for cracks or breaks.
  3. Tighten any loose clamps or replace damaged hoses as needed.
  4. Check the intake manifold gasket for leaks and replace if necessary.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor from the intake duct using a Torx or Phillips screwdriver.
  3. Clean the MAF sensor with MAF cleaner (do not use other cleaners) and let it dry.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Inspect Fuel System

• Sub-steps:
  1. Use a fuel pressure gauge to check the fuel pressure at the fuel rail.
  2. If pressure is low, inspect the fuel pump and fuel filter; replace the fuel filter if it has not been changed recently.
  3. Ensure the fuel injectors are functioning properly; consider cleaning or replacing them if necessary.

5. Check and Repair Vacuum Leaks

• Sub-steps:
  1. Inspect all vacuum lines for cracks, breaks, or disconnections.
  2. Use a smoke machine or carburetor cleaner to identify any vacuum leaks during idle.
  3. Replace any damaged vacuum hoses as needed.