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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to detect leaks around the intake manifold and vacuum lines.
  • Replace any damaged hoses or gaskets found during inspection.

3. Check and Clean MAF Sensor

• Sub-steps:
  • Locate the MAF sensor; it is typically found in the air intake duct between the air filter and throttle body.
  • Disconnect the electrical connector from the MAF sensor.
  • Remove the MAF sensor from its housing using a Torx or socket wrench.
  • Clean the MAF sensor with MAF cleaner spray (do not use brake cleaner).
  • Reinstall the MAF sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  • Attach a fuel pressure gauge to the fuel rail test port.
  • Turn the ignition key to the ON position (do not start) and observe the fuel pressure reading.
  • Compare the reading to the manufacturer's specifications (typically around 50-60 psi).
  • If the pressure is low, inspect the fuel pump, fuel filter, and fuel pressure regulator for issues.

5. Inspect Fuel Injectors

• Sub-steps:
  • Remove the engine cover if necessary to access the fuel injectors.
  • Visually check for any fuel leaks around the injectors.
  • Use a multimeter to test the resistance of each injector (should be within manufacturer specs).
  • If injectors are clogs or faulty, replace them with new ones.

6. Reconnect Battery and Clear Codes

• Sub-steps:
  • Reconnect the negative battery terminal.
  • Use the OBD-II scanner to clear the P0174 code from the engine's computer.
  • Start the engine and allow it to idle for a few minutes.