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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, wrench set
• Check all vacuum hoses connected to the intake manifold for cracks or damage.
• Tighten or replace any loose or damaged hoses.
• Use a vacuum gauge to confirm system integrity.

3. Clean the Mass Airflow Sensor

• Tools Required: MAF cleaner or isopropyl alcohol, soft cloth
• Carefully remove the MAF sensor from the air intake duct.
• Spray MAF cleaner on the sensor element and allow it to dry completely before reinstalling.
• Reinstall the MAF sensor securely.

4. Check Fuel System

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "ON" position without starting the engine and check the fuel pressure reading.
• If the pressure is below specifications (refer to manufacturer specs), inspect or replace the fuel pump and filter.

5. Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set
• Locate the upstream oxygen sensor and disconnect the electrical connector.
• Remove the sensor using the O2 sensor socket.
• Install the new oxygen sensor and reconnect the electrical connector.