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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust jack stands.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery by removing the negative terminal to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (typically near the exhaust manifold and before the catalytic converter).
  2. Disconnect the electrical connectors from the sensors.
  3. Use a socket wrench to unscrew the sensors from their respective locations.
  4. Install the new sensors by screwing them into place and reconnecting the electrical connectors.
  5. Torque the sensors to the manufacturer's specifications (usually around 30-40 ft-lbs).

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

• Sub-steps:
  1. Inspect the catalytic converter for any physical damage or blockage.
  2. If replacement is needed, use the socket set to unbolt the catalytic converter from the exhaust system.
  3. Remove the old catalytic converter and install the new one, ensuring proper alignment.
  4. Torque the bolts to the manufacturer's specifications (typically around 30-40 ft-lbs).
  5. Reconnect any exhaust hangers removed during the process.

4. Reset the OBD-II System

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
  3. Start the engine and let it run until it reaches operating temperature.