how to fix P0171 lean code on Toyota Corolla E170 (2013-2019)?

Solution

1. Preparation

• Gather tools and materials: OBD-II scanner, fuel pressure gauge, multimeter, MAF cleaner, vacuum gauge, and basic hand tools.
• Ensure the vehicle is parked on a level surface, and the engine is cool.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, basic hand tools
• Instructions:
  1. Start the engine and allow it to reach operating temperature.
  2. Use a vacuum gauge to check for normal readings (typically between 15-22 inHg).
  3. Inspect all vacuum hoses for cracks or disconnections; replace any damaged hoses.
  4. Check the intake manifold gasket for leaks and replace if necessary.

3. Check and Clean MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver
• Instructions:
  1. Disconnect the MAF sensor connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Spray the MAF sensor with MAF cleaner and allow it to dry completely.
  4. Reinstall the MAF sensor and reconnect the connector.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Instructions:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Connect the fuel pressure gauge to the test port.
  3. Turn the ignition to the ON position (without starting the engine) and check the pressure; it should be within manufacturer specifications (typically around 43-50 psi).
  4. If the pressure is low, check the fuel pump and filter for issues and replace as necessary.

5. Inspect and Test Fuel Injectors

• Tools Required: Multimeter, injector cleaning kit
• Instructions:
  1. Use a multimeter to check the resistance of each fuel injector; it should match manufacturer specifications (usually around 12-16 ohms).
  2. If any injector is out of spec, replace it.
  3. Optionally, perform an injector cleaning procedure if they are clogged.