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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Hose clamps, vacuum gauge, and a flashlight.
• Inspect all vacuum hoses for cracks or breaks. Replace any damaged hoses.
• Check the intake manifold gasket for leaks. If damaged, replace the gasket.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver.
• Remove the MAF sensor from the air intake duct.
• Spray MAF cleaner onto the sensor elements carefully. Allow it to dry before reinstalling.
• If the MAF sensor is faulty, replace it with a new one.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition on (do not start the engine) and check the fuel pressure. It should be within the manufacturer's specifications (typically around 40-50 psi). If low, inspect the fuel pump and filter for issues.
• Replace the fuel filter if it is clogged.

5. Test and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket and wrench.
• Use a multimeter or scan tool to test the upstream oxygen sensor's voltage output.
• If the sensor is not functioning properly, remove it using an O2 sensor socket and replace it with a new one.

6. Reassemble and Clear Codes

• Reconnect any disconnected components and reattach the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Use the OBD-II scanner to clear the P0171 code and check if it reappears.