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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before proceeding.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake system for cracks or disconnections.
  2. Apply a smoke test if necessary to detect leaks.
  3. Replace any damaged hoses or gaskets identified during the inspection.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the mass air flow sensor in the air intake duct.
  2. Disconnect the electrical connector from the MAF sensor.
  3. Remove the sensor using the appropriate socket.
  4. Clean the MAF sensor with MAF cleaner spray and allow it to dry.
  5. Reinstall the sensor and reconnect the electrical connector.

4. Check Fuel System

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position without starting the engine to check the fuel pressure.
  3. Compare the reading to the manufacturer's specifications (usually around 40-50 psi).
  4. If the pressure is low, inspect the fuel pump, filter, and pressure regulator for issues.
  5. Replace any faulty components.

5. Inspect and Clean Throttle Body

• Sub-steps:
  1. Remove the air intake duct to access the throttle body.
  2. Use a throttle body cleaner and a soft cloth to clean the throttle plate and interior surfaces.
  3. Ensure the throttle plate moves freely and does not stick.
  4. Reassemble the intake duct securely.