how to fix P0420 code in Genesis G70 IG (2017-2023)

Solution

1. Preparation

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

2. Inspect and Test Oxygen Sensors

• Remove the upstream and downstream oxygen sensors using an oxygen sensor socket.
• Use a multimeter to check the voltage output of the upstream sensor (should fluctuate between 0.1V and 0.9V).
• Perform the same test for the downstream sensor; it should remain relatively stable.
• If either sensor is faulty, replace it with a new one.

3. Check Catalytic Converter

• If the oxygen sensors are functioning correctly, inspect the catalytic converter for physical damage or blockage.
• Use a pyrometer to measure the inlet and outlet temperatures of the catalytic converter; the outlet should be at least 100°F hotter than the inlet under load.
• If the catalytic converter is defective, replace it with a new unit.

4. Repair Exhaust Leaks

• Inspect the exhaust system for leaks, particularly before the catalytic converter.
• Tighten any loose connections or replace damaged gaskets and pipes as necessary.

5. Reassemble and Reconnect

• Reinstall the oxygen sensors if they were removed.
• Reconnect the battery and ensure all connections are tight.
• Clear the error codes using the OBD-II scanner.