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

Solution

1. Preparation

• Gather the necessary tools and parts.
• Disconnect the battery to prevent electrical issues.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench.
• Remove the negative battery cable.
• Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Use the O2 sensor socket and wrench to unscrew the sensors.
• Inspect the sensors for damage; replace them if they are faulty.
• Install the new sensors:
  • Apply anti-seize compound to the threads (if applicable).
  • Torque to manufacturer's specifications (typically around 30-40 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, gasket scraper.
• Inspect the catalytic converter for physical damage or blockage.
• If replacement is necessary, remove the exhaust pipe bolts connected to the catalytic converter.
• Use a gasket scraper to remove old gaskets from the exhaust manifold and the catalytic converter.
• Install the new catalytic converter:
  • Position the new unit and attach it to the exhaust pipe and manifold.
  • Torque bolts to manufacturer's specifications (usually around 40-50 ft-lbs).
• Reinstall any heat shields or associated components.

4. Clear Codes and Test

• Reconnect the negative battery cable.
• Use the OBD-II scanner to clear the codes from the ECU.
• Start the vehicle and allow it to reach operating temperature.