how to address the P0171 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on any components.

2. Inspect and Replace Air Intake Components

• Inspect Air Filter:

  • Remove the air filter housing.
  • Check the air filter for dirt and restrictions; replace if necessary.

• Inspect Intake Hoses:

  • Visually inspect all intake hoses for cracks, tears, or loose connections.
  • Tighten or replace any faulty hoses as needed.

3. Test and Clean MAF Sensor

• Remove MAF Sensor:

  • Disconnect the electrical connector.
  • Unscrew and carefully remove the MAF sensor from the air intake.

• Clean MAF Sensor:

  • Use MAF sensor cleaner spray (do not use other cleaners).
  • Spray the cleaner on the sensor element and allow it to dry completely before reinstalling.

4. Check and Replace Fuel System Components

• Test Fuel Pressure:

  • Connect a fuel pressure gauge to the fuel rail.
  • Turn the ignition to the "ON" position without starting the engine to check the pressure.
  • Compare the reading to the manufacturer's specifications; replace the fuel pump if pressure is low.

• Inspect Fuel Injectors:

  • Remove the fuel rail and inspect injectors for clogs or leaks.
  • Clean or replace injectors as necessary.

5. Clear Codes and Recheck

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0171 code from the ECM.
• Start the engine and observe for any check engine light re-illumination.