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

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps
• Visually inspect all vacuum hoses for cracks or disconnections.
• Use a vacuum gauge to test the intake manifold; replace any damaged hoses.
• Tighten any loose connections to ensure a proper seal.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, Torx screwdriver
• Disconnect the MAF sensor electrical connector.
• Remove the MAF sensor from the air intake duct.
• Spray the MAF sensor with MAF cleaner, taking care not to touch the sensor elements.
• Allow it to dry completely before reinstalling. If damaged, replace the MAF sensor.

4. Fuel System Check

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition on without starting the engine and check the fuel pressure.
• If the pressure is below specifications (typically 30-50 psi), check the fuel pump and filter; replace them if necessary.

5. Throttle Body Cleaning

• Tools Required: Throttle body cleaner, cleaning cloth
• Remove the air intake duct to access the throttle body.
• Spray throttle body cleaner onto a cloth and wipe the inside of the throttle body to remove carbon deposits.
• Reassemble the air intake duct and ensure all connections are secure.

6. Oxygen Sensor Test

• Tools Required: Multimeter, O2 sensor socket
• Disconnect the oxygen sensor from the exhaust system.
• Use a multimeter to check the voltage output of the sensor; it should vary between 0.1V to 0.9V.
• Replace the oxygen sensor if it is out of this range or shows a constant voltage.