why does my Toyota RAV4 XA50 (2019-2024) have a check engine light and code P0171?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before starting work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamp pliers, flashlight.
• Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Use a vacuum gauge to test the intake system for leaks; repair or replace any faulty hoses.
• Ensure that the intake manifold is securely fastened and that the gaskets are in good condition.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, socket set.
• Disconnect the MAF sensor electrical connector and remove the sensor from the air intake.
• Spray the MAF sensor with MAF cleaner, avoiding touching the sensor elements.
• Allow it to dry completely before reinstalling.
• If the sensor is damaged, replace it with a new one.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Locate the fuel rail test port; connect the fuel pressure gauge.
• Turn the ignition key to the "ON" position (do not start the engine) to pressurize the system.
• Verify that the fuel pressure is within the manufacturer's specifications (typically between 30-50 psi).
• If pressure is low, inspect the fuel pump and filter for issues.

5. Clear Codes and Test Drive

• Reconnect the battery terminal and use the OBD-II scanner to clear the P0171 code.
• Start the engine and monitor for any abnormal sounds or behaviors.
• Take the vehicle for a test drive under different conditions (idle, acceleration) to ensure the issue is resolved.