how to fix the P0420 code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter, socket set.
• Remove the upstream oxygen sensor using the appropriate socket.
• Test the sensor's resistance and voltage output; replace if faulty.
• Repeat for the downstream oxygen sensor.

3. Inspect Catalytic Converter

• Tools Required: Socket set, pry bar, flashlight.
• Check for physical damage or excessive rust on the catalytic converter.
• If damaged or clogged, proceed to remove the catalytic converter.
• Remove the exhaust bolts securing the converter to the exhaust pipe and manifold.
• Carefully detach the catalytic converter from the exhaust system.

4. Replace Catalytic Converter (if necessary)

• Parts Required: New catalytic converter.
• Install the new catalytic converter by aligning it with the exhaust system.
• Torque the bolts to the manufacturer’s specifications (usually between 25-30 lb-ft).
• Reconnect any oxygen sensors that were removed.

5. Reassemble and Reconnect Battery

• Reinstall any shields or heat guards that were removed.
• Lower the vehicle and reconnect the negative battery terminal.