I was driving my '96 Accord EX 4-cyl merrily along the freeway when suddenly the check engine light comes out. I borrowed my neighbor's OBDII scanner (it's made by Actron) and it returns the code P0141. I looked up the code and it says "O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)". I researched a little into that and I think that's the secondary O2 sensor by the cats but I am not too sure.

Anyone familiar with the car I have knows exactly which sensor it is? And where exactly it is located on the car and how does it look like? Looking under the hood, I see 2 two green plugs that kinda look like the O2 sensor I saw on the web while I was doing my research. One is facing the radiator and the other is on top of the engine block next to the inner side row of the spark plugs. I don't think either of those is the one I am looking for. So how many O2 sensors are there on my car? Appreciate any help you guys can give me.