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.
• Ensure the vehicle is on a level surface and securely raised if needed.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses and connections for wear or damage.
  • Use a smoke machine or carburetor cleaner to detect leaks; listen for changes in engine RPM.
  • Replace any damaged hoses or gaskets found during inspection.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Disconnect the MAF sensor connector.
  • Remove the MAF sensor from the air intake duct using a screwdriver.
  • Clean the MAF sensor with MAF cleaner spray; allow it to dry completely before reinstalling.
  • Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel Pressure

• Sub-steps:
  • Locate the fuel rail and connect the fuel pressure gauge to the test port.
  • Turn the ignition key to the "ON" position (do not start the engine) and read the pressure.
  • Compare the reading to manufacturer specifications (typically between 50-60 psi for most Toyota engines).
  • If pressure is low, check the fuel pump and fuel filter for issues; replace as necessary.

5. Inspect and Test Fuel Injectors

• Sub-steps:
  • Remove the fuel injector connectors and the fuel rail (be cautious of fuel spillage).
  • Perform a flow test on each injector to ensure they are delivering the correct volume.
  • Clean or replace any injectors that are clogged or malfunctioning.