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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Hose clamps, vacuum gauge
• Check all vacuum hoses for cracks or damage. Replace any damaged hoses.
• Inspect the intake manifold for leaks. Use a smoke machine or spray soapy water to identify leaks.
• Tighten any loose connections and ensure all clamps are secure.

3. Check and Clean the MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver
• Locate the MAF sensor in the air intake duct.
• Remove the MAF sensor using a screwdriver.
• Spray the MAF sensor with MAF cleaner to remove dirt and debris. Allow it to dry completely before reinstalling.
• Reinstall the MAF sensor securely.

4. Inspect Fuel System

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the ON position (do not start) and observe the pressure reading. It should match the manufacturer’s specifications (typically around 30-50 PSI depending on the engine).
• If the pressure is low, inspect the fuel pump and fuel filter for issues and replace if necessary.

5. Check Fuel Injectors

• Tools Required: Injector cleaner, multimeter
• Use a multimeter to check the resistance of each fuel injector. Compare readings against manufacturer specifications.
• If injectors are clogged, use injector cleaner or consider replacing them.

6. Reassemble and Clear Codes

• Reconnect any components removed during inspection and repair.
• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0174 code from the ECM.