how to fix P0171 code on Volkswagen Passat B8 (2015-2022)?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Hose clamp pliers, spray bottle with soapy water.
• Inspect all vacuum lines connected to the intake manifold.
• Apply soapy water to suspected areas and look for bubbles indicating leaks.
• Replace any damaged hoses or gaskets found during inspection.

3. Clean MAF Sensor

• Tools Required: MAF sensor cleaner.
• Locate the MAF sensor in the intake system.
• Disconnect the electrical connector and remove the MAF sensor from the housing.
• Spray the MAF sensor with cleaner and allow it to dry completely before reinstalling.

4. Check Fuel System

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "ON" position (do not start the engine) to check fuel pressure. It should match the manufacturer's specifications (usually around 50-60 psi).
• If the pressure is low, inspect the fuel pump and fuel filter for issues and replace if necessary.

5. Inspect Oxygen Sensors

• Tools Required: O2 sensor socket.
• Locate and remove the front oxygen sensor using the O2 sensor socket.
• Inspect the sensor for damage or contamination.
• If necessary, replace the oxygen sensor with a new one following manufacturer specifications.

6. Reassemble and Test

• Reconnect all components, ensuring all connectors and hoses are secure.
• Reconnect the negative battery terminal.
• Start the engine and check for any new codes using the OBD-II scanner.