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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.
• Ensure the vehicle is on a flat surface and secure it with wheel chocks.

2. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks around intake gaskets and vacuum connections.
  3. Replace any damaged hoses or gaskets as necessary.

3. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Locate the fuel rail pressure test port and connect the fuel pressure gauge.
  2. Turn the ignition to the "ON" position (without starting the engine) to check the initial pressure.
  3. Compare the reading with manufacturer specifications (typically around 50-60 psi for Highlanders).
  4. If pressure is low, check for fuel pump operation and replace the fuel filter if necessary.

4. Test the MAF Sensor

• Tools Required: Multimeter
• Sub-steps:
  1. Disconnect the MAF sensor connector.
  2. Use a multimeter to check the voltage output while gently revving the engine.
  3. Compare the voltage readings with specifications (typically 0.5 to 4.5 volts).
  4. Replace the MAF sensor if readings are outside the manufacturer’s specifications.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the engine cover to access fuel injectors.
  2. Disconnect the fuel injector connectors.
  3. Use a multimeter to test the resistance of each injector (typically 12-16 ohms).
  4. Clean injectors using a professional cleaning kit or replace if faulty.

6. Reassemble and Reset Systems

• Sub-steps:
  1. Reconnect all connectors and hoses that were removed or inspected.
  2. Reconnect the negative battery terminal.
  3. Clear the P0174 code using an OBD-II scanner.