1. Check and replace parts: You suspect that there is a problem with a specific part, such as a three-way catalytic converter, so you need to check and replace this part.
2. Clear the fault code: The vehicle is equipped with on-board diagnosis system, and you can try to clear the fault code, which can be done with the instrument panel open.
3. Restart the vehicle: Sometimes, restarting the vehicle can temporarily solve this problem. You can try turning the ignition switch to the on position and then turning it off. Then restart the engine and check the indicator light. The indicator light is still on, so you need to ask a professional to check the vehicle as soon as possible.