how to fix the P0171 code on my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery negative terminal to prevent electrical shock.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:

  1. Visually inspect all vacuum hoses and connections for cracks or disconnections.
  2. Use a smoke machine to detect hidden leaks, if available.
  3. Replace any damaged hoses or gaskets as needed.

• Tools Required:

  • Smoke machine (optional)
  • Hose clamp pliers

3. Clean or Replace MAF Sensor

• Sub-steps:

  1. Remove the MAF sensor from the air intake duct.
  2. Clean the MAF sensor using MAF sensor cleaner spray.
  3. If cleaning does not resolve the issue, replace the MAF sensor with a new one.

• Tools Required:

  • Torx or Phillips screwdriver
  • MAF sensor cleaner

4. Check Fuel Pressure

• Sub-steps:

  1. Connect a fuel pressure gauge to the fuel rail Schrader valve.
  2. Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading.
  3. If the pressure is below the manufacturer's specification, check the fuel pump and fuel filter; replace if necessary.

• Tools Required:

  • Fuel pressure gauge
  • Wrench set

5. Inspect and Clean Fuel Injectors

• Sub-steps:

  1. Remove the fuel rail with injectors attached.
  2. Inspect injectors for clogs or leaks.
  3. Clean the injectors using a specialized injector cleaner or replace them if necessary.

• Tools Required:

  • Injector cleaning kit (if cleaning)
  • Socket set

6. Test Oxygen Sensor

• Sub-steps:

  1. Use a multimeter to check the voltage output of the upstream oxygen sensor.
  2. If the voltage is not fluctuating between 0.1 to 0.9 volts while the engine is running, consider replacing the sensor.

• Tools Required:

  • Multimeter