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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from their respective locations.
  4. Install new oxygen sensors by screwing them into place and tightening to the manufacturer's specifications (typically 30-40 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Wrench set, socket set, torque wrench, exhaust pipe cutter (if necessary).
• Sub-steps:
  1. Inspect the catalytic converter for any signs of damage or blockage.
  2. If replacement is necessary, unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  3. If applicable, use an exhaust pipe cutter to remove the converter.
  4. Install the new catalytic converter, ensuring to use new gaskets as needed.
  5. Torque the bolts to the manufacturer's specifications (typically 22-30 ft-lbs).

4. Clear Codes and Test

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  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.