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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical issues during repair.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter.
• Remove the oxygen sensor from the exhaust manifold (pre-catalytic) and the downstream sensor (post-catalytic).
• Use a multimeter to test the sensors for proper voltage output. Replace any sensors that are out of spec.
• Torque the new sensors to the manufacturer’s specifications (typically around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torch wrench, exhaust hanger removal tool.
• Remove the exhaust pipes connected to the catalytic converter, starting with any clamps or bolts.
• If applicable, detach the heat shield and any sensors attached to the catalytic converter.
• Remove the catalytic converter from its mounting brackets using the socket set.
• Install the new catalytic converter, ensuring that all gaskets are replaced, and torque the bolts to manufacturer specifications.
• Reattach any heat shields and sensors.

4. Clear Codes and Test Drive

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Test drive the vehicle for at least 20 minutes to allow the engine management system to recalibrate and monitor for any new codes.