how to fix P0420 code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Raise the vehicle safely using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors in the exhaust system.
2. Use a socket wrench to carefully remove the upstream oxygen sensor.
3. Inspect the sensor for any signs of damage or contamination; replace if necessary.
4. Repeat the process for the downstream oxygen sensor.
5. Install new sensors and tighten them to the manufacturer's torque specifications (typically around 30 lb-ft).
6. Reconnect the battery terminal.

3. Replace the Catalytic Converter (if necessary)

1. Remove any mounting bolts securing the catalytic converter to the exhaust system.
2. If applicable, disconnect any heat shields or brackets.
3. Carefully remove the catalytic converter from its position—ensure any gaskets or seals are removed.
4. Install the new catalytic converter, ensuring it is aligned correctly with the exhaust system.
5. Reattach all mounting bolts and tighten to specifications (usually around 30 lb-ft).
6. Replace any gaskets or seals to prevent exhaust leaks.

4. Clear the Codes and Test

1. Reconnect the OBD-II scanner and clear the P0420 code from the vehicle's computer.
2. Start the engine and allow it to reach normal operating temperature.
3. Take the vehicle for a test drive to ensure the check engine light does not reappear.