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.

 

There are two. Both are in the cat or one is in the cat and one is in the collector of the exhaust manifold. Replace the one furthest downstream of exhaust flow.

 

I think I just found the O2 sensor furthest downstream of the exhaust flow. It's right by the cat which is right under the center of the car

I was hoping it would be easy to get to. Thanks for the help.