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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and set the parking brake.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Check the upstream oxygen sensor (sensor 1) by measuring the voltage; it should oscillate between 0.1V and 0.9V.
• If the sensor is faulty, replace it with a new one, ensuring proper connections.

3. Inspect Catalytic Converter

• Tools Required: Socket set, torque wrench
• Remove any heat shields covering the catalytic converter.
• Inspect the catalytic converter for physical damage or signs of clogging (e.g., rattling sound when shaken).
• If damaged, remove the catalytic converter using a socket set and replace it with a new unit, tightening bolts to manufacturer specifications.

4. Reassemble and Reset

• Reinstall any heat shields removed during inspection.
• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.