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

Solution

1. Preparation

• Gather all necessary tools and parts before starting.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before starting work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps
• Inspect all vacuum hoses and connections for cracks or disconnections.
• Use a vacuum gauge to check for leaks; repair or replace any damaged hoses.
• Reattach any disconnected hoses and ensure secure connections.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver
• Locate the MAF sensor in the intake system.
• Disconnect the electrical connector and unscrew the sensor from the housing.
• Clean the sensor using MAF sensor cleaner; allow it to dry completely.
• Reinstall the MAF sensor and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge
• Locate the fuel pressure test port on the fuel rail.
• Attach the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
• Check the fuel pressure reading against the specifications in the repair manual; if it's low, inspect the fuel pump and filter.
• If necessary, replace the fuel filter or fuel pump.

5. Inspect Fuel Injectors

• Tools Required: Injector cleaning kit (if cleaning), replacement injectors (if needed)
• Remove the fuel rail to access the fuel injectors.
• Inspect each injector for clogs or leaks. Clean them using an injector cleaning kit if clogged.
• If any injectors are faulty, replace them with new ones.

6. Reassemble and Reset Codes

• Reinstall any components that were removed during the inspection.
• Reconnect the negative battery terminal.
• Start the engine and allow it to reach normal operating temperature.
• Use the OBD-II scanner to clear the P0171 code and check for any reoccurrences.