how to fix P0174 code on Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather all tools and parts needed.
• Disconnect the negative battery terminal for safety.
• Allow the engine to cool down before working on it.

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, vacuum gauge, flashlight
• Check intake manifold and vacuum hoses:
  1. Visually inspect for any visible cracks or disconnections.
  2. Use a vacuum gauge to check for any vacuum leaks.
  3. If leaks are found, replace damaged hoses or use sealant on cracks.

3. Test and Replace MAF Sensor (if necessary)

• Tools Required: Multimeter, screwdriver
• Test the MAF sensor:
  1. Disconnect the MAF sensor connector.
  2. Use a multimeter to measure the voltage output while the engine is running.
  3. Compare the readings to manufacturer specifications; if out of range, replace the MAF sensor.

4. Check Fuel System

• Tools Required: Fuel pressure gauge, socket set
• Check the fuel pressure:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "On" position without starting the engine and check the pressure against specifications.
  3. If pressure is low, inspect the fuel pump and filter for blockages or failure and replace if necessary.

5. Inspect Fuel Injectors

• Tools Required: Socket set, cleaning kit
• Inspect fuel injectors:
  1. Remove the fuel rail and injectors from the intake manifold.
  2. Check for clogs and clean injectors using a cleaning kit or replace if damaged.

6. Verify ECT Sensor Functionality

• Tools Required: Multimeter
• Test the ECT sensor:
  1. Disconnect the ECT sensor connector.
  2. Use a multimeter to measure resistance and compare it to manufacturer specifications.
  3. Replace the sensor if readings are incorrect.