how can I fix the P0171 code on my Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent electrical shock.
• Allow the engine to cool down before starting.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold and throttle body.
  2. Use a smoke machine or spray soapy water to identify leaks while the engine runs.
  3. Replace any damaged or cracked hoses.

Tools Required:

• Smoke machine or soapy water solution

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the sensor with MAF cleaner spray; avoid touching the sensor element.
  4. Reinstall the MAF sensor and reconnect the wiring.

Tools Required:

• MAF cleaner spray
• Screwdriver set

4. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the ON position (do not start the engine) to check the fuel pressure.
  3. Compare the reading to manufacturer specifications; replace the fuel pump or filter if pressure is low.

Tools Required:

• Fuel pressure gauge

5. Clean Throttle Body

• Sub-steps:
  1. Remove the air intake duct to access the throttle body.
  2. Use throttle body cleaner and a soft cloth to clean the interior of the throttle body.
  3. Reassemble the air intake duct securely.

Tools Required:

• Throttle body cleaner
• Soft cloth
• Torque wrench (for reassembly)