My car showed an engine fault at 3000 kilometers, asking to check the emission system. Should I use 92 or 95 octane fuel for this car? Can someone with expertise help out?

You can just use 92 octane.

In this situation, it's common for new cars to experience issues like this. It might be caused by poor fuel quality. Another possibility is a fault with the catalytic converter. For this new car, using 92-octane gasoline should be fine.