I don't think it's an O2 sensor light. Either it's a 'maintenance reminder' light to get you to service the EGR and emissions system, or it's the 'check engine light' trying to tell you that the computer has detected a fault in the engine/emissons control system. Get it checked out by a pro. If you want to find a specialist, here's a directory link for you: https://repairpal.com/directory?address=33435&car_brand_names=Isuzu
My friend reset mine. He's a retired mechanic. All he did was remove the instrument cluster from the dash and short the wire for the O2 sensor. Get a shop manual for it before trying this fix. Just to make sure you don't damage it trying to reset it.