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

Solution

1. Preparation

• Gather all tools and parts required for the repair.
• Disconnect the negative terminal of the battery to prevent electrical issues.
• Allow the vehicle to cool down if recently driven.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• 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 sensors from their respective locations.
  4. Install the new sensors by threading them into place and tightening them to the manufacturer's specifications (usually 30-40 ft-lbs).
  5. Reconnect the electrical connectors to both sensors.

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

• Tools Required: Socket set, cutting torch or saw (if necessary), exhaust pipe clamps, gasket material.
• Sub-steps:
  1. Inspect the catalytic converter for physical damage or signs of clogging.
  2. If replacement is required, disconnect the exhaust pipes from the catalytic converter using a socket set.
  3. If there are welded connections, use a cutting torch or saw to remove the old catalytic converter carefully.
  4. Install the new catalytic converter, ensuring any gaskets are replaced and that the exhaust pipes are properly aligned.
  5. Tighten all clamps and connections to the manufacturer's specified torque.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECM.