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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the vehicle to cool down before working on the exhaust system.

2. Inspect and Test Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Use a multimeter to test the voltage output of both sensors while the engine is running.
  • Upstream Sensor: Should show varying voltage between 0.1V and 0.9V.
  • Downstream Sensor: Should show a relatively stable voltage (less than 0.5V).
• Replace any faulty sensors with OEM parts.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench
• If oxygen sensors are functioning properly, inspect the catalytic converter.
• Remove the catalytic converter from the exhaust system.
  • Sub-steps:
    • Unbolt the exhaust flanges and any brackets securing the catalytic converter.
    • Carefully lower and remove the old catalytic converter.
• Install the new catalytic converter and secure it with bolts.
  • Torque Specification: Follow the manufacturer's torque specification for exhaust components.
• Reinstall the oxygen sensors in the correct order.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes before taking it for a test drive to ensure the issue is resolved.