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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety.
• Raise the vehicle securely on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream (pre-catalytic) oxygen sensor:
  • Disconnect the electrical connector.
  • Use the O2 sensor socket to unscrew the sensor.
• Install the new upstream oxygen sensor:
  • Apply anti-seize compound to the threads.
  • Torque to manufacturer specifications (typically around 30 lb-ft).
  • Reconnect the electrical connector.
• Repeat for the downstream (post-catalytic) oxygen sensor if it was found faulty.

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

• Tools Required: Socket set, torque wrench, gasket scraper
• Remove the catalytic converter:
  • Disconnect the exhaust pipes at both ends of the catalytic converter.
  • Remove mounting bolts and brackets.
• Inspect the catalytic converter for damage or blockage; if found defective, replace it with a new unit.
• Ensure to replace any gaskets and use new bolts if required.
• Torque all bolts to the manufacturer’s specifications.

4. Reassemble and Reconnect

• Reconnect the exhaust system, ensuring all components are secured.
• Reconnect the battery.