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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Remove the upstream oxygen sensor using the O2 sensor socket.
• Inspect the sensor for damage; replace if necessary.
• Reinstall the new upstream sensor and torque to manufacturer's specification (typically around 30-40 ft-lbs).
• Repeat the process for the downstream oxygen sensor if it is found faulty.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, cutting tools (if necessary), exhaust gasket sealant.
• Remove the exhaust pipe bolts connecting to the catalytic converter using the socket set.
• If the converter is welded, use cutting tools to remove it carefully.
• Install the new catalytic converter, ensuring proper alignment.
• Reattach the exhaust pipe and bolts, tightening to the specified torque.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Test drive the vehicle under various conditions to ensure the issue is resolved.