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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to prevent any electrical shorts.
• Allow the engine to cool completely before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Inspect the upstream and downstream oxygen sensors for damage. If faulty:
  • Use an O2 sensor socket to remove the old sensor(s).
  • Apply anti-seize compound to the threads of the new sensor.
  • Install the new sensor(s) and torque to manufacturer specifications (typically around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, gasket scraper.
• If the catalytic converter is blocked or damaged:
  • Remove the exhaust pipes connected to the catalytic converter using a socket set.
  • Clean any gasket material from the mounting surfaces.
  • Install the new catalytic converter and secure with bolts, torquing to specified values (usually around 25 lb-ft).

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory.