When you open the hood, you will see the bank 1 sensor 1 o2 installed at the top of the exhaust manifold. bank 1 sensor 2 is on the bottom side of that same manifold. The warm up tip is a good one. Also disconnect the sensors before removing them and tighten them before connecting.
for the most part its on the exhaust somewhere give these websites a try www.autozone.com and www.alldatadiy.com if all fails stop by your local Hyundai dealership in the parts department and they will print you out a picture and diagram showing you where its located wish you the best Michigan Man.
they are the only sensors that are plugged into the exhaust system. follow exhaust from engine u will spot them. replacement tip- get exhaust warm 120 F or so to help with replacement. cold exhaust makes it much harder to replace. if u have a 6 cylinder engine there may be more then 2 sensors