how to fix P0420 code on Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.
• Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the oxygen sensor(s) located pre-catalytic converter and post-catalytic converter.
• Inspect the sensors for damage; if faulty, replace with new OEM sensors.
• Torque the new oxygen sensor to the manufacturer’s specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter (if needed), new gaskets, exhaust sealant
• Remove the bolts securing the catalytic converter to the exhaust system.
• If necessary, use an exhaust pipe cutter to free the catalytic converter from the exhaust system.
• Install the new catalytic converter, ensuring to use new gaskets and exhaust sealant as required.
• Torque the bolts to specifications (check vehicle service manual for specific torque values).

4. Clear Codes and Test Drive

• Reconnect the battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the vehicle and conduct a test drive to ensure no codes reappear and to verify the vehicle’s performance has returned to normal.