what causes a P0174 code on my Toyota Corolla E140 (2006-2013)

Learn how to diagnose and fix P0174 lean fuel condition in Toyota Corolla E140 (2006-2013). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or loose connections.
  2. Use a smoke machine or propane torch (with caution) to detect leaks.
  3. Replace any damaged hoses or fittings as necessary.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor from the air intake duct using a Torx screwdriver.
  3. Clean the sensor with MAF cleaner spray; do not touch the sensor element.
  4. Allow the sensor to dry, then reinstall it and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position (do not start) and check the pressure reading.
  3. If the pressure is below specification (usually around 40-50 psi), check the fuel pump and filter.
  4. Replace the fuel filter if clogged, and assess the fuel pump for functionality.

5. Inspect Throttle Body

• Sub-steps:
  1. Remove the air intake duct to access the throttle body.
  2. Clean the throttle body with throttle body cleaner to remove carbon deposits.
  3. Carefully open the throttle plate to clean the inner surfaces.
  4. Reinstall the air intake duct securely.