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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal for safety.

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 wiring harness from each sensor.
  3. Use the O2 sensor socket to remove the old sensors.
  4. Install the new sensors into their respective locations, tightening to the manufacturer's specification (typically around 30 lb-ft).
  5. Reconnect the wiring harness to each sensor.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Sub-steps:
  1. Visually inspect the catalytic converter for damage. If it is damaged or if the code persists after replacing the sensors, proceed with replacement.
  2. Use a socket set to remove any bolts securing the catalytic converter to the exhaust system.
  3. If necessary, cut the exhaust pipe with an exhaust cutter to remove the catalytic converter.
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Tighten all bolts to the manufacturer's torque specifications.

4. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Clear the P0420 code using the OBD-II scanner and perform a test drive to monitor for reoccurrence.