how to fix my Toyota Highlander Fourth Generation (2020-present) check engine light P0420

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent any electrical issues during the repair.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors.
2. Using a socket wrench, carefully disconnect the electrical connectors of both sensors.
3. Remove the sensors using an oxygen sensor socket or wrench.
4. Compare the old sensors with new ones to ensure compatibility.
5. Install the new oxygen sensors and torque them to the manufacturer's specifications (typically around 30-40 ft-lbs).
6. Reconnect the electrical connectors to the sensors.

3. Examine and Replace the Catalytic Converter (if necessary)

1. Inspect the catalytic converter for signs of damage, blockage, or excessive carbon build-up.
2. If replacement is needed, support the vehicle securely on jack stands.
3. Remove the bolts or clamps securing the catalytic converter to the exhaust system using a socket set.
4. Carefully detach the catalytic converter from the exhaust system.
5. Install the new catalytic converter in reverse order, ensuring all bolts and clamps are tightened to the manufacturer’s torque specifications.
6. Reconnect any exhaust hangers or supports that were removed.

4. Reset the Check Engine Light

1. Reconnect the battery to restore power to the vehicle.
2. Use the OBD-II scanner to clear the P0420 code and reset the check engine light.
3. Start the engine and allow it to reach operating temperature.