how to fix P0171 code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool completely before starting work.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks while the engine is idling.
  3. Replace any damaged hoses or gaskets as needed.

3. Check and Clean the MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector from the sensor.
  3. Remove the MAF sensor using a Torx screwdriver.
  4. Clean the sensor with MAF cleaner spray; do not touch the sensing element.
  5. Reinstall the sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  1. Locate the fuel rail and remove the service port cap.
  2. Connect the fuel pressure gauge to the service port.
  3. Turn the ignition key to the "On" position (do not start) and check the fuel pressure reading.
  4. Compare the reading with the manufacturer's specifications (typically 40-50 psi for the Corolla).
  5. If pressure is low, check the fuel pump and filter for issues.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel injector connectors and inspect for damage.
  2. Use a multimeter to check for proper resistance (typically 12-16 ohms).
  3. If necessary, remove the injectors, clean them with a professional injector cleaner, or replace them if faulty.