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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical issues.
• Allow the engine to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream oxygen sensor using the O2 sensor socket.
• Install the new upstream oxygen sensor and torque to manufacturer specifications (usually around 30 lb-ft).
• Repeat for the downstream oxygen sensor if necessary.

3. Replace Catalytic Converter (if needed)

• Tools Required: Socket set, cutting torch (if welded), exhaust hanger tool
• Support the vehicle on jack stands and ensure it is secure.
• Remove the exhaust hangers to free the catalytic converter.
• Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
• If the converter is welded, carefully cut the welds to remove it.
• Install the new catalytic converter, ensuring that it is properly aligned.
• Torque the bolts to manufacturer specifications (typically around 25 lb-ft).
• Reinstall the exhaust hangers securely.

4. Clear Codes and Test Drive

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes.
• Take the vehicle for a test drive to ensure the check engine light does not reappear and monitor performance.