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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on any components.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to identify leaks around the intake manifold and vacuum lines.
  • Replace any faulty hoses or repair leaks found during inspection.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Remove the air intake duct to access the MAF sensor.
  • Disconnect the electrical connector from the MAF sensor.
  • Remove the MAF sensor from the housing.
  • Use MAF sensor cleaner to clean the sensor elements. Do not use other types of cleaners as they may damage the sensor.
  • Reinstall the MAF sensor and reconnect the electrical connector.
  • Reassemble the air intake duct.

4. Check Fuel Pressure

• Sub-steps:
  • Locate the fuel pressure test port on the fuel rail.
  • Connect the fuel pressure gauge to the test port.
  • Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading.
  • If fuel pressure is below the manufacturer's specification (usually around 43-50 psi), check the fuel pump and fuel filter for proper operation.
  • Replace the fuel filter if necessary and test the fuel pump for function.

5. Test Fuel Injectors

• Sub-steps:
  • Use a multimeter to check the resistance of the fuel injectors. Compare readings to specifications in the service manual.
  • Inspect for fuel leaks around the injectors and replace any faulty injectors.
  • Perform an injector cleaning if they are clogged.