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

Solution

1. Preparation

• Gather all tools and parts needed.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on it.

2. Inspect for Vacuum Leaks

• Use a smoke machine or carburetor cleaner to check for leaks.
• If a leak is found, replace any damaged vacuum hoses or gaskets.

3. Clean the Mass Airflow Sensor

• Remove the MAF sensor from the intake duct.
• Use MAF cleaner to gently clean the sensor. Allow it to dry completely before reinstalling.
• Reinstall the MAF sensor securely.

4. Check Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "ON" position without starting the engine and check the pressure reading against manufacturer's specifications (typically around 43-50 psi).
• If pressure is low, consider replacing the fuel pump or fuel filter.

5. Inspect Fuel Injectors

• Disconnect the fuel injector connectors and perform a resistance test with a multimeter.
• Clean or replace any clogged fuel injectors as necessary.

6. Test Oxygen Sensors

• Use a multimeter to check the voltage output of the upstream oxygen sensor while the engine is running.
• If the readings are outside of the normal range (typically 0.1-0.9 volts), consider replacing the oxygen sensor.