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

Solution

1. Preparation

• Gather 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 Air Intake System

• Inspect Air Filter:
  • Remove the air filter and check for dirt or obstructions; replace if necessary.
• Check for Leaks:
  • Visually inspect the intake manifold and throttle body for any signs of leaks; tighten or replace as needed.

3. Clean or Replace MAF Sensor

• Remove MAF Sensor:
  • Disconnect the electrical connector and remove the screws holding the MAF sensor in place.
• Clean MAF Sensor:
  • Use MAF sensor cleaner to spray the sensing element; do not touch it.
• Reinstall Sensor:
  • Reattach the MAF sensor and connector securely.

4. Check Fuel System

• Test Fuel Pressure:
  • Connect a fuel pressure gauge to the fuel rail and compare readings with manufacturer specifications (typically 50-60 psi for most vehicles).
• Replace Fuel Filter:
  • If fuel pressure is low, replace the fuel filter according to service manual instructions.

5. Inspect and Replace Vacuum Hoses

• Visual Inspection:
  • Inspect all vacuum hoses for cracks, wear, or disconnections.
• Replace Damaged Hoses:
  • Use appropriate hose clamps and ensure connections are secure.

6. Check and Replace ECT Sensor (if necessary)

• Remove ECT Sensor:
  • Disconnect the electrical connector and unscrew the sensor from the engine.
• Install New ECT Sensor:
  • Apply thread sealant and install the new sensor, then reconnect the electrical connector.