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 engage the parking brake.
• Disconnect the battery to prevent electrical shocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for damage or carbon buildup; replace if necessary.
• Torque new sensors to manufacturer specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Remove the exhaust pipe bolts securing the catalytic converter using the socket set.
• Carefully detach the catalytic converter from the exhaust system, using the exhaust hanger removal tool if needed.
• Inspect the mounting surfaces for any damage or debris, then install the new catalytic converter, ensuring it is properly aligned.
• Torque the mounting bolts to manufacturer specifications (usually around 30 lb-ft).

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer system.