how to fix P0171 code on my Volkswagen Golf MK7 (2015-2019)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down if it has been running.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, socket set, torque wrench
• Visually inspect all vacuum lines and intake manifold gaskets for signs of wear or damage.
• Use a vacuum gauge to test for leaks. If a leak is found, replace the affected line or gasket.
• Torque all intake manifold bolts to the manufacturer’s specification (generally around 10 Nm).

3. Clean Mass Air Flow (MAF) Sensor

• Tools Required: MAF cleaner
• Carefully remove the MAF sensor from the air intake duct.
• Spray the MAF cleaner onto the sensor elements without touching them.
• Allow it to dry completely before reinstalling the MAF sensor.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (do not start the engine) and check the fuel pressure. It should match the manufacturer’s specifications.
• If the pressure is low, check the fuel pump and fuel filter for issues. Replace as necessary.

5. Replace Engine Coolant Temperature (ECT) Sensor (if faulty)

• Tools Required: Socket set, torque wrench
• Locate the ECT sensor on the engine and disconnect the electrical connector.
• Remove the sensor using a socket and replace it with a new one, ensuring it is properly torqued to specifications (generally around 15 Nm).
• Reconnect the electrical connector.