how to fix P0171 code on Toyota Highlander XU70 (2020-Present)

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, basic hand tools.
• Use a vacuum gauge to check for leaks in the intake manifold and vacuum lines.
• Repair or replace any damaged hoses or gaskets found during the inspection.
• Reconnect any disconnected hoses securely.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver set.
• Remove the MAF sensor from the intake duct carefully.
• Spray the sensor with MAF cleaner and allow it to dry completely.
• Reinstall the MAF sensor and ensure all connections are secure.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail's test port.
• Turn the ignition to the ON position (do not start the engine) and check the fuel pressure reading against manufacturer's specifications (typically around 50-60 psi).
• If pressure is low, check the fuel pump and filter for issues.

5. Inspect and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit, basic hand tools.
• Remove the fuel injectors from the fuel rail.
• Use a fuel injector cleaning kit to clean the injectors or replace them if they are clogged.
• Reinstall the fuel injectors and ensure proper sealing.

6. Reassemble and Reset

• Reconnect 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 monitor for any reoccurrence.