how to fix P0420 code on Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather all required tools and parts.
• Disconnect the vehicle battery to ensure safety during repairs.
• Allow the engine to cool down completely.

2. Inspect and Replace Oxygen Sensors

1. Locate the Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the Sensors: Carefully unplug the connectors from both sensors.
3. Remove the Sensors: Use an oxygen sensor socket to unscrew and remove both sensors from the exhaust system.
4. Install New Sensors: Apply anti-seize compound to the threads of the new oxygen sensors and install them in the same locations.
5. Reconnect the Sensors: Plug the connectors back into the new sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components: If the catalytic converter is found to be faulty, detach any heat shields and exhaust pipes connected to it using a socket set.
2. Remove the Catalytic Converter: Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
3. Install New Catalytic Converter: Position the new catalytic converter in place and secure it with the bolts to the exhaust manifold and exhaust pipe.
4. Reattach Exhaust Components: Reinstall any heat shields and exhaust components that were removed.

4. Clear Codes and Test

1. Reconnect the Battery: Ensure all connections are secure and reconnect the battery.
2. Clear OBD-II Codes: Use the scanner to clear the P0420 code from the ECU.
3. Test Drive: Drive the vehicle under various conditions to monitor performance and ensure the check engine light does not return.