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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Allow the exhaust system to cool before beginning work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil (if needed).
• Remove the upstream (pre-catalytic) oxygen sensor using the O2 sensor socket.
• Inspect the sensor for damage; replace if faulty.
• Install the new sensor and torque to manufacturer specifications (usually around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary), gasket scraper, high-temperature exhaust sealant.
• Remove the bolts holding the catalytic converter to the exhaust manifold and exhaust pipe.
• Inspect the converter for damage or blockage.
• If replacement is needed, install the new catalytic converter using new gaskets and hardware.
• Torque the bolts to manufacturer specifications (typically 40-50 ft-lbs).

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Test drive the vehicle to ensure the check engine light does not reappear and that the vehicle operates normally.