how to fix P0171 code on my Toyota Highlander XU70 (2020-Present)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during the repair process.

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, flashlight
• Steps:
  1. Remove the engine cover (if applicable) using the socket set.
  2. Visually inspect the air intake duct for cracks or loose connections.
  3. Tighten any loose clamps and replace any damaged hoses or ducts.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver
• Steps:
  1. Disconnect the MAF sensor electrical connector.
  2. Remove the MAF sensor from the air intake using a screwdriver.
  3. Spray MAF sensor cleaner onto the sensing elements and allow it to dry completely.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Test and Repair Fuel System

• Tools Required: Fuel pressure gauge
• Steps:
  1. Connect the fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "ON" position (do not start) and check the fuel pressure reading against manufacturer specifications.
  3. If the pressure is low, inspect and replace the fuel pump or fuel filter as needed.

5. Inspect and Replace Vacuum Hoses

• Tools Required: Pliers, replacement vacuum hoses
• Steps:
  1. Locate all vacuum hoses connected to the intake manifold and engine.
  2. Inspect for cracks, breaks, or loose connections.
  3. Replace any damaged or deteriorated vacuum hoses with new ones.

6. Check and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, torque wrench
• Steps:
  1. Use the O2 sensor socket to remove the upstream oxygen sensor from the exhaust manifold.
  2. Install the new O2 sensor and torque it to the manufacturer’s specifications (usually around 30 lb-ft).
  3. Reconnect the electrical connector.