how to fix P0420 code on my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, exhaust pressure gauge, socket set, jack and jack stands.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Raise the vehicle using a jack and secure with jack stands for safety.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Using a socket, carefully remove the oxygen sensors from the exhaust pipe.
  4. Install new oxygen sensors by threading them into the exhaust pipe and tightening to manufacturer specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors to the new oxygen sensors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for any signs of damage, discoloration, or rattling.
  2. If replacement is necessary, unbolt the catalytic converter from the exhaust system using the socket set, ensuring to remove any heat shields if applicable.
  3. Install the new catalytic converter, ensuring proper alignment and sealing.
  4. Torque all bolts to manufacturer specifications (typically around 40-50 ft-lbs).

4. Clear Codes and Test

• 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 allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.