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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Ensure the engine is cool before starting work.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses for cracks or disconnections.
  • Use a smoke machine to detect hidden leaks if necessary.
  • Replace any damaged hoses with new ones, ensuring a tight fit to prevent leaks.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Remove the MAF sensor from the intake duct using a screwdriver.
  • Clean the MAF sensor with MAF cleaner spray, avoiding contact with the sensor element.
  • Allow the sensor to dry completely before reinstalling it. If damaged, replace it with a new sensor.

4. Check Fuel Pressure

• Sub-steps:
  • Attach a fuel pressure gauge to the fuel rail's service port.
  • Turn the ignition to the ON position (do not start the engine) and check the pressure reading.
  • If the pressure is below specifications (typically 40-50 psi), inspect the fuel pump and filter for issues.

5. Inspect Fuel Injectors

• Sub-steps:
  • Disconnect the electrical connector from each fuel injector.
  • Use a multimeter to measure the resistance across the injector terminals (specification typically 12-16 ohms).
  • Replace any injectors that do not meet resistance specifications.

6. Test ECT Sensor

• Sub-steps:
  • Locate the ECT sensor and disconnect its electrical connector.
  • Use a multimeter to measure the resistance of the sensor at different temperatures (refer to the manufacturer's specifications).
  • Replace the ECT sensor if it is out of specification.