how to fix P0174 code in Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down before starting work.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to identify leaks.
  3. Replace any damaged hoses or gaskets found during inspection.
• Tools Required: Smoke machine or carburetor cleaner, screwdriver, replacement hoses.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor on the air intake tube.
  2. Disconnect the electrical connector and remove the sensor from the housing.
  3. Clean the sensor with MAF cleaner; avoid touching the sensor element.
  4. If damaged, replace it with a new MAF sensor.
• Tools Required: Torx or socket set, MAF cleaner.

4. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition key to the "ON" position (do not start) to check the pressure.
  3. Ensure the pressure matches the manufacturer’s specifications (typically around 50-60 psi).
  4. If the pressure is low, check the fuel pump and filter.
• Tools Required: Fuel pressure gauge.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail to access the injectors.
  2. Inspect injectors for clogging or leaks.
  3. Clean or replace any faulty injectors.
• Tools Required: Socket set, injector cleaning kit or replacement injectors.

6. Reassemble and Test

• Sub-steps:
  1. Reassemble any components removed during the repair.
  2. Reconnect the negative battery terminal.
  3. Start the engine and allow it to reach operating temperature.
• Tools Required: Basic hand tools.