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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the pre-catalytic and post-catalytic oxygen sensors using the O2 sensor socket.
• Inspect the sensors for any signs of contamination or damage.
• If faulty, replace with new OEM or equivalent sensors.
• Torque the new sensors to manufacturer specifications (typically around 30 ft-lbs).

3. Inspect the Catalytic Converter

• Tools Required: Socket set, torque wrench.
• If the oxygen sensors are functional, check the catalytic converter for any physical damage or blockage.
• Remove the catalytic converter by loosening the bolts securing it to the exhaust system.
• Inspect the internal structure of the catalytic converter; if damaged or clogged, replace it with a new one.
• Reinstall the new catalytic converter and torque the bolts to manufacturer specifications.

4. Clear the Codes

• Tools Required: OBD-II scanner.
• After repairs, reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECU.
• Start the engine and allow it to reach operating temperature.