what does the P0171 code indicate for my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect the air intake duct and connections for any signs of damage or disconnection.
  2. If any leaks are found, replace the damaged sections with OEM parts.
  3. Reconnect any loose connections securely.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake system.
  2. Disconnect the electrical connector.
  3. Remove the MAF sensor using the appropriate socket or screwdriver.
  4. If cleaning, use MAF sensor cleaner; spray gently onto the sensor elements. Allow it to dry completely.
  5. If replacement is necessary, install the new sensor according to the manufacturer's specifications.

4. Check and Repair Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "ON" position without starting the engine and read the fuel pressure.
  3. If the pressure is low, inspect the fuel pump and filter for issues, replacing them as needed.

5. Inspect and Repair Vacuum Lines

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks, breaks, or disconnections.
  2. Replace any damaged hoses with new ones, ensuring proper routing and connection.

6. Reconnect Battery and Clear Codes

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0171 code from the ECM.