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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust pipe cutter (if necessary).
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, penetrating oil (if sensors are rusted).
• Remove the upstream (before the catalytic converter) and downstream (after the catalytic converter) oxygen sensors.
• Inspect the sensors for damage; replace if necessary.
• Install new oxygen sensors and torque to manufacturer specifications (typically around 30 Nm).

3. Inspect and Replace Catalytic Converter (if needed)

• Tools Required: Socket set, exhaust pipe cutter (if applicable), gasket scraper.
• Remove the exhaust pipe bolts connecting to the catalytic converter.
• If blocking or damage is found, cut the exhaust pipe at the connection points if necessary.
• Remove the old catalytic converter and clean the mating surface on the exhaust system.
• Install the new catalytic converter and ensure proper alignment.
• Torque the bolts to manufacturer's specifications (typically around 40 Nm).

4. Reset the Engine Control Module (ECM)

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to reset the check engine light and clear the P0420 code from the ECM.