how to fix P0171 code in Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is on a flat surface and the engine is cool.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Screwdriver set, vacuum gauge.
• Sub-steps:
  1. Visually inspect all vacuum lines connected to the intake manifold for cracks or disconnections.
  2. Use a vacuum gauge to check for leaks; a vacuum reading significantly lower than the manufacturer's specification indicates a leak.
  3. Replace any damaged vacuum hoses or gaskets.

3. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner or isopropyl alcohol, clean lint-free cloth.
• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor from the air intake duct.
  3. Spray MAF cleaner onto the sensing elements; do not touch them with any tools or fingers.
  4. Allow it to dry completely before reinstalling.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Sub-steps:
  1. Locate the fuel rail and connect the fuel pressure gauge to the service port.
  2. Turn the ignition to the "ON" position without starting the engine and check the fuel pressure.
  3. Compare the reading with the specifications found in the service manual, typically around 43-50 psi.
  4. If the pressure is low, check the fuel pump, filter, and injectors for issues.

5. Inspect Throttle Body

• Tools Required: Throttle body cleaner, soft brush.
• Sub-steps:
  1. Remove the air intake duct from the throttle body.
  2. Use throttle body cleaner and the soft brush to clean any carbon buildup inside the throttle body.
  3. Reinstall the air intake duct securely.