how to troubleshoot P0420 code on Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on the vehicle.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the electrical connectors from both sensors.
3. Use an O2 sensor socket or wrench to remove the old sensors.
4. Install new oxygen sensors, ensuring they are tightened to the manufacturer’s specifications (typically 30-40 Nm).
5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter

1. If the catalytic converter is found to be faulty, locate the bolts securing it to the exhaust system.
2. Use a socket set to remove the bolts and any hangers connected to the catalytic converter.
3. Carefully remove the old catalytic converter from the exhaust system.
4. Install the new catalytic converter, ensuring proper alignment with the exhaust pipes.
5. Torque the bolts to the manufacturer’s specifications (typically 40-50 Nm).

4. Reconnect Battery and Clear Codes

1. Reconnect the battery terminals securely.
2. Use the OBD-II scanner to clear the P0420 code from the ECU.
3. Start the engine and allow it to reach operating temperature.