how do I fix the P0420 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the engine is cool and disconnect the negative battery terminal.
• Tools Required: OBD-II scanner, socket set, wrench set, vacuum gauge, exhaust gas analyzer.

2. Inspect and Replace Oxygen Sensors

• Remove the oxygen sensor wiring harness connectors.
• Using the appropriate socket, remove the upstream (pre-catalytic) oxygen sensor.
• Inspect the sensor for wear and replace if necessary.
• Repeat the process for the downstream (post-catalytic) oxygen sensor.
• Tools Required: Oxygen sensor socket, ratchet, and extension.

3. Inspect and Replace Catalytic Converter

• If the oxygen sensors are functioning properly, proceed to replace the catalytic converter.
• Support the vehicle on jack stands and remove the exhaust pipe connections to the catalytic converter.
• Remove the mounting bolts holding the catalytic converter in place.
• Install the new catalytic converter by reversing the removal process, ensuring all gaskets are in good condition and properly aligned.
• Torque the bolts to the manufacturer's specifications (typically around 30-40 ft-lbs, check service manual for exact values).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Tools Required: OBD-II scanner.