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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool if it has been running.

2. Inspect and Replace Sensors

1. Remove the upstream oxygen sensor (O2 sensor):

   • Use an O2 sensor socket or wrench to unscrew the sensor.
   • Disconnect the electrical connector.

2. Install the new upstream O2 sensor:

   • Apply anti-seize compound on the threads (if not pre-applied).
   • Torque to manufacturer specification (typically around 30 lb-ft).
   • Reconnect the electrical connector.

3. Repeat for the downstream O2 sensor:

   • Follow the same steps as above for the downstream O2 sensor.

3. Inspect and Replace the Catalytic Converter

1. Remove exhaust components:

   • Use a socket set to unbolt the exhaust system from the catalytic converter.
   • Unclamp and remove any exhaust hangers if needed.

2. Inspect the catalytic converter:

   • Check for physical damage, carbon buildup, or rattling.

3. Install the new catalytic converter:

   • Position the new converter in place.
   • Reattach all bolts and clamps, ensuring proper alignment.
   • Torque bolts to manufacturer specifications.

4. Clear the Code

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.

5. Test Drive

• Start the vehicle and allow it to reach operating temperature.
• Conduct a test drive to monitor performance and ensure no codes reappear.