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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the engine is cool before beginning repairs.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps
• Visually inspect all vacuum hoses connected to the intake manifold and surrounding components.
• Use a vacuum gauge to check for leaks in the system.
• Repair or replace any damaged hoses, ensuring secure connections with hose clamps.

3. Check and Repair Air Intake System

• Tools Required: Torque wrench, gasket scraper
• Remove the air intake duct and visually inspect for any cracks or leaks.
• Check the throttle body gasket and intake manifold gasket for signs of wear. Replace as necessary.
• Reinstall the air intake duct and ensure all clamps and gaskets are properly torqued to manufacturer specifications.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Locate the fuel pressure test port on the fuel rail.
• Connect the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
• Check the fuel pressure reading against manufacturer specifications (typically around 50-60 psi for most Toyota models).
• If pressure is low, inspect the fuel pump and fuel filter for possible replacement.

5. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner, screwdriver
• Disconnect the MAF sensor electrical connector.
• Remove the MAF sensor from the air intake assembly using a screwdriver.
• Clean the sensor with MAF cleaner; do not touch the sensor element.
• Reinstall the MAF sensor and reconnect the electrical connector.

6. Inspect Fuel Injectors

• Tools Required: Fuel injector cleaning kit, multimeter
• Remove the fuel injectors from the fuel rail.
• Use a multimeter to check the resistance of each injector; compare to specifications.
• Clean the injectors with a fuel injector cleaning kit or replace if faulty.