check engine, O2 faults.. 96 318i

[bbojangles]

I have 2 codes being thrown.. P0136 and P1186
oxygen sensor fault. Bank 1 Circuit 2 I reset the fault with my reader, but it came back after a few km.

I have not yet crawled under the car. but I think there are 2 O2 sensors in the 318, pre and post cat.

which one is heated? which one is bank 1 Circuit 2?

also ... anyone have a line as to where to buy a sensor in Canada.. (toronto)

[propr'one]

if its after cat, dont bother replacing it, it doesn't do anything.

[bbojangles]

Fair enough, but again, I ask whick one is causing the fault?

I gotta say that is absolutely against my knowledge of BMW engineering to add something that "doesn't do any thing"

And if it is not replaced, then the check engine light is on. How would I know if anything else is wrong?

[bbojangles]

nobody knows which sensor throws the P0136 and P1186 codes on a 318?