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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical issues.

2. Inspect and Repair Air Intake System

• Sub-steps:
  • Visually inspect air intake hoses for cracks or loose connections.
  • Tighten or replace any damaged hoses as necessary.
  • Check the air filter for cleanliness and replace if clogged.

3. Test and Clean MAF Sensor

• Sub-steps:
  • Locate the MAF sensor and disconnect its electrical connector.
  • Remove the MAF sensor from the air intake.
  • Use MAF sensor cleaner to clean the sensor elements. Allow it to dry completely before reinstalling.
  • Reinstall the MAF sensor and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail test port.
  • Turn the ignition to the “ON” position (do not start the engine) and check the pressure reading.
  • Compare the reading with the manufacturer specifications (usually around 35-50 psi for most Toyota engines). If low, consider replacing the fuel pump or fuel filter.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  • Remove the fuel rail to access the fuel injectors.
  • Inspect the injectors for any clogs or leaks.
  • Use an ultrasonic cleaner or injector cleaner to clean the injectors if necessary.
  • Reinstall the fuel rail and ensure all connections are secure.