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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent any electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the electrical connectors from both oxygen sensors.
3. Use an oxygen sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
4. Install new oxygen sensors by threading them into place and tightening to manufacturer specifications (typically around 30 lb-ft).
5. Reconnect the electrical connectors for both sensors.

3. Inspect and Replace the Catalytic Converter

1. If the oxygen sensors are functioning correctly and the code persists, inspect the catalytic converter.
2. Remove the exhaust pipe and any heat shields if necessary to access the catalytic converter.
3. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
4. Install the new catalytic converter, ensuring that gaskets are in place and secure the bolts to the specified torque (usually around 25 lb-ft).
5. Reinstall any heat shields and exhaust components that were removed.

4. Clear Codes and Test

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