how to fix P0171 code on my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

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

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, screwdriver set, vacuum gauge
• Inspect the air intake hoses and connections for cracks or loose fittings. Replace any damaged hoses as necessary.
• Use the vacuum gauge to check for leaks in the intake manifold. Repair any leaks found.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver set
• Remove the MAF sensor from the air intake duct.
• Use MAF sensor cleaner to spray the sensor gently, ensuring not to touch the sensor element.
• Allow the sensor to dry completely before reinstalling. If damaged, replace with a new MAF sensor.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge, safety goggles
• Connect the fuel pressure gauge to the fuel rail and turn the ignition to the "ON" position without starting the engine to check the pressure.
• If pressure is below specifications, inspect the fuel pump and replace if necessary.

5. Inspect Fuel Injectors

• Tools Required: Fuel injector cleaner kit, socket set
• Visually inspect the fuel injectors for leaks or clogs.
• Use a fuel injector cleaning kit to clean the injectors if they are clogged. Replace them if they are leaking.

6. Test and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, multimeter
• Use a multimeter to test the oxygen sensors for proper voltage output. Replace any sensors that are outside of specification.