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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a level surface and engage the parking brake.
• Disconnect the negative battery terminal to avoid electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Use a smoke machine or carburetor cleaner to check for leaks in the vacuum lines.
  2. Replace any damaged or cracked hoses.
  3. Inspect the intake manifold gaskets and replace if necessary.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF sensor cleaner
• Sub-steps:
  1. Locate the MAF sensor, typically found in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor.
  3. Spray the MAF sensor with the appropriate cleaner and allow it to dry.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Check and Adjust Fuel System

• Sub-steps:
  1. Attach a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position without cranking the engine to check for fuel pressure.
  3. If pressure is below specifications, check the fuel pump, filter, and lines for issues.
  4. Replace any faulty components as needed.

5. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor in the exhaust system.
  2. Use a multimeter to test the sensor's voltage output (should fluctuate between 0.1 and 0.9 volts).
  3. If the sensor is faulty, replace it according to the manufacturer's specifications.