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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts during repair.
• Allow the vehicle to cool before starting work on exhaust components.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: The upstream (pre-catalytic) sensor is located before the catalytic converter, and the downstream (post-catalytic) sensor is located after it.
2. Remove the sensors:
   • Use a 22mm oxygen sensor socket.
   • Turn counter-clockwise to remove both sensors.
3. Install new sensors:
   • Apply anti-seize compound on the threads of the new sensors.
   • Install the upstream sensor first, followed by the downstream sensor, turning clockwise until snug.
   • Torque specification: Approximately 30 ft-lbs.
4. Reconnect the battery.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust system components:
   • Use a socket set to unbolt the exhaust flange connecting the catalytic converter to the exhaust manifold.
   • Remove any hangers or brackets securing the catalytic converter.
2. Inspect the catalytic converter: Look for signs of blockage or physical damage.
3. Install the new catalytic converter:
   • Position the new converter in place.
   • Reattach the exhaust flange using the original bolts and torque to manufacturer specifications.
   • Reinstall any hangers or brackets.
4. Check exhaust leaks: Start the engine and listen for any exhaust leaks around the installation area.