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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the upstream sensor first, followed by the downstream sensor if needed.
  4. Install new oxygen sensors by screwing them into place and reconnecting the electrical connectors.
  5. Torque the sensors to the manufacturer's specifications (typically around 30 ft-lbs).

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

• Tools Required: Socket set, cutting tool (if needed), torque wrench.
• Sub-steps:
  1. Inspect the catalytic converter for any cracks or physical damage.
  2. If replacement is needed, remove the exhaust pipes connected to the catalytic converter using the socket set.
  3. For welded converters, use a cutting tool to remove the old converter.
  4. Install the new catalytic converter, ensuring proper alignment and tightening all bolts to the specified torque (usually 30-40 ft-lbs).
  5. Reconnect any exhaust pipes previously removed.

4. Clear Codes and Test

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Start the engine and let it idle for a few minutes.
  4. Take the vehicle for a short test drive to ensure no codes return.