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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, penetrating oil (if needed).
• Remove the upstream and downstream oxygen sensors by applying penetrating oil to the threads if they are corroded.
• Install new oxygen sensors, ensuring they are securely tightened to the manufacturer's specifications (typically around 30-35 Nm).
• Reconnect the battery.

3. Replace the Catalytic Converter (if necessary)

• Tools Required: Jack and jack stands or a lift, socket set, torque wrench, exhaust gasket.
• Raise the vehicle securely using a jack and jack stands.
• Locate the catalytic converter and disconnect the exhaust pipes as necessary (remove bolts/nuts and any hangers).
• Remove the old catalytic converter and replace it with a new one, ensuring correct alignment and that any gaskets are replaced.
• Tighten all connections to the manufacturer's torque specifications (usually around 40-50 Nm).
• Lower the vehicle back to the ground.

4. Final Checks

• Reconnect the battery and start the engine.
• Allow the vehicle to idle and check for leaks around the exhaust system.
• Test drive the vehicle to ensure the check engine light does not return.