how to solve P0171 code in my Volkswagen Passat B8 (2015-2022)

Solution

1. Preparation

• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Gather tools and parts for the repair.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually examine the entire air intake duct for cracks or loose clamps.
  2. Replace any damaged hoses or tighten loose connections.
  3. If applicable, clean the air filter and replace it if it is dirty.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor's electrical connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the sensor using MAF cleaner spray, avoiding any contact with the sensor element.
  4. If malfunctioning, replace the MAF sensor with a new OEM part.

4. Test and Repair Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "ON" position (do not start the engine) and check the fuel pressure; it should match manufacturer specifications (usually around 50-60 psi).
  3. If the pressure is low, inspect the fuel pump and filter for clogs or failures and replace as necessary.
  4. If injectors are faulty, remove and replace them with new units.

5. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor on the exhaust manifold.
  2. Disconnect the oxygen sensor's electrical connector and remove it using an oxygen sensor socket.
  3. Install the new sensor and reconnect the electrical connector.