how to fix P0171 lean code in Volkswagen Tiguan First Generation (2007-2018)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Repair Air Intake System

• Inspect Vacuum Hoses:

  • Visually check all vacuum lines for cracks or disconnections.
  • Replace any damaged hoses.

• Check Gaskets:

  • Inspect intake manifold and throttle body gaskets for leaks.
  • Replace gaskets as necessary.

3. Clean or Replace MAF Sensor

• Remove MAF Sensor:

  • Disconnect the electrical connector and remove screws securing the MAF sensor.

• Clean MAF Sensor:

  • Use MAF cleaner spray to clean the sensor. Avoid touching the sensor element.

• Reinstall MAF Sensor:

  • Reattach the sensor and secure it with screws. Reconnect the electrical connector.

4. Inspect Fuel System

• Check Fuel Pressure:

  • Use a fuel pressure gauge to check fuel pressure at the fuel rail. Compare with specifications (typically 50-60 psi for Tiguan).

• Replace Fuel Filter:

  • If pressure is low, consider replacing the fuel filter if it hasn't been changed as per maintenance schedule.

5. Test and Replace Oxygen Sensors (if necessary)

• Check Oxygen Sensor Functionality:

  • Use a multimeter to check the voltage output of the upstream O2 sensor. It should fluctuate between 0.1 and 0.9 volts.

• Replace Oxygen Sensor:

  • If the sensor is faulty, replace it by unscrewing it from the exhaust manifold and installing the new one.