how to fix P0171 code in Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts, and ensure the vehicle is parked on a flat surface.
• Disconnect the battery to prevent electrical shocks while working on the vehicle.

2. Inspect and Replace Vacuum Lines

• Sub-steps:
  1. Locate all vacuum lines connected to the intake manifold.
  2. Visually inspect each line for cracks, wear, or disconnections.
  3. Replace any damaged lines with new vacuum hose of the same diameter.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor from the air intake tube using a socket set.
  3. Clean the MAF sensor with MAF cleaner spray. Avoid touching the sensor elements.
  4. If cleaning does not resolve the issue, replace the MAF sensor with a new one.

4. Check and Replace Fuel Filter (if necessary)

• Sub-steps:
  1. Locate the fuel filter and relieve fuel pressure from the system.
  2. Disconnect the fuel lines from the filter using a line wrench.
  3. Replace the filter with a new one, ensuring proper orientation.
  4. Reconnect the fuel lines and check for leaks.

5. Test the Fuel Injectors

• Sub-steps:
  1. Locate the fuel injectors and inspect their connectors for damage.
  2. Use a multimeter to check the resistance of each injector; it should match the manufacturer's specifications.
  3. If any injector is faulty, replace it with a new one.
  4. Reconnect all components and the battery.