how to fix P0420 code in my Genesis G70 IG (2017-2023) after replacing the O2 sensor

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the battery to prevent electrical shorts during repairs.

2. Inspect and Test the Catalytic Converter

• Tools Required: Infrared thermometer, exhaust pressure gauge
• Sub-steps:
  1. Start the engine and allow it to reach operating temperature.
  2. Use an infrared thermometer to measure the temperature at the inlet and outlet of the catalytic converter.
     • Inlet temperature should be significantly lower than the outlet if the converter is functioning properly (ideally, the outlet should be 100-150°F hotter).
  3. If the temperature difference is minimal, the catalytic converter may be failing.

3. Check for Exhaust Leaks

• Tools Required: Smoke machine (or similar device)
• Sub-steps:
  1. Use a smoke machine to introduce smoke into the exhaust system.
  2. Look for smoke escaping from any joints or areas along the exhaust system.
  3. Repair any leaks found, as they can affect the readings from the O2 sensors.

4. Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, penetrating oil
• Sub-steps:
  1. If the catalytic converter is confirmed to be faulty, raise the vehicle and secure it on jack stands.
  2. Remove the exhaust hangers and bolts securing the catalytic converter to the exhaust system.
  3. Carefully detach the converter from the exhaust pipes.
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Torque the bolts to the manufacturer’s specifications.
  6. Reattach exhaust hangers and ensure everything is secure.