how to diagnose P0171 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

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

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect the air intake hoses for cracks or loose connections.
  2. Tighten any loose clamps or replace damaged hoses.
  3. If leaks are found, replace the affected components.

3. Check and Clean MAF Sensor

• Sub-steps:
  1. Remove the MAF sensor from the air intake duct using a socket set.
  2. Clean the MAF sensor using MAF cleaner; avoid touching the sensor elements.
  3. Reinstall the MAF sensor securely.

4. Test and Replace Fuel Pressure Regulator (if necessary)

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position without starting the engine and check the pressure.
  3. If the pressure is below specification, replace the fuel pressure regulator.

5. Inspect and Repair Fuel Injectors

• Sub-steps:
  1. Locate fuel injectors on the engine.
  2. Check for any fuel leaks around the injectors.
  3. If there are clogs, use a fuel injector cleaner or replace the injectors if necessary.