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

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, screwdriver set
• Sub-steps:
  1. Use a vacuum gauge to test for leaks in the intake manifold and vacuum lines.
  2. Replace any damaged or cracked hoses or gaskets.
  3. Reconnect all hoses securely and ensure clamps are tight.

3. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner, Torx screwdriver
• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor.
  3. Clean the sensor gently with MAF cleaner, avoiding contact with the sensor element.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge, wrenches
• Sub-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 pressure reading.
  3. Compare the reading to the specifications for your vehicle (typically between 50-60 psi).
  4. If pressure is low, check the fuel pump and replace if necessary.

5. Test and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit, multimeter
• Sub-steps:
  1. Remove the fuel rail with the injectors attached.
  2. Use a multimeter to test the resistance of each injector; replace any that are out of specification.
  3. Clean the injectors using a fuel injector cleaning kit according to the manufacturer's instructions.
  4. Reinstall the fuel rail and ensure all connections are secure.

6. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Clear the P0171 code using the OBD-II scanner.
• Start the engine and let it idle to check for any reoccurring codes.