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

Solution

1. Preparation

• Gather the necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors based on the vehicle’s service manual.
2. Use an oxygen sensor socket to carefully remove the upstream oxygen sensor.
3. Install the new upstream oxygen sensor and torque it to the manufacturer's specifications (typically 30-35 ft-lbs).
4. Repeat the process for the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Visually inspect the catalytic converter for any physical damage or signs of clogging.
2. If replacement is needed, loosen the exhaust clamps and remove the exhaust pipe connected to the catalytic converter.
3. Remove the catalytic converter from its mounting brackets.
4. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
5. Reattach the exhaust pipe and secure with clamps, torquing to manufacturer specifications.

4. Clear Codes and Test

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