how to fix Toyota Corolla E210 (2019-2024) check engine light error code P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle’s battery to prevent electrical shorts.
• Allow the engine to cool before proceeding with repairs.

2. Oxygen Sensor Replacement (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Locate the upstream (pre-catalytic) oxygen sensor on the exhaust manifold.
• Remove the sensor by turning it counterclockwise using the O2 sensor socket.
• Install the new oxygen sensor by threading it in and tightening it to the manufacturer's specified torque (typically around 30 ft-lbs).
• Reconnect the electrical connector.

3. Catalytic Converter Inspection/Replacement (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter (if necessary).
• Inspect the catalytic converter for any external damage or signs of blockage.
• If replacement is needed, support the exhaust system with a jack.
• Disconnect the exhaust pipes from the catalytic converter using a socket set, and cut if necessary.
• Remove the catalytic converter from its mounting brackets.
• Install the new catalytic converter by securing it in place and reconnecting the exhaust pipes.
• Ensure all connections are tight and free from leaks.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the check engine light codes.
• Start the vehicle and allow it to reach operating temperature.