my Toyota Corolla E140 (2006-2013) has a check engine light with code P0171, what does it mean?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the car is parked on a level surface and the engine is cool.
• Disconnect the battery for safety.

2. Inspect Air Intake System

• Remove the air intake hose using a socket set.
• Visually inspect for cracks or loose connections.
• Replace any damaged hoses or clamps.

3. Clean or Replace the MAF Sensor

• Remove the MAF sensor from the air intake duct.
• Use MAF sensor cleaner to clean the sensor element carefully.
• Allow it to dry before reinstalling. If damaged, replace the MAF sensor.

4. Check and Adjust Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (not starting) to check pressure.
• If the pressure is below specifications, check the fuel pump and fuel filter for issues.
• Replace the fuel filter if clogged and consider replacing the fuel pump if necessary.

5. Inspect Fuel Injectors

• Use a socket set to remove the fuel rail and access the injectors.
• Check for clogs and leaks; clean or replace injectors as needed.
• Reinstall the fuel rail, ensuring proper torque specifications.

6. Check Engine Coolant Temperature Sensor

• Locate the coolant temperature sensor, typically near the thermostat housing.
• Disconnect the electrical connector and use a multimeter to test the sensor's resistance.
• Replace the sensor if it does not meet specifications.