On a OEM configuration for placement of the oxygen sensor. The upstream sensor should be on the exhaust manifold, and the downstream sensor should be right after the first catalytic converter. I keep getting a CEL for a unheated circuit, and just ended up buying a OEM replacement for the upstream sensor to see if this would correct the problem, but would like some clarification if my placement is correct.

Thanks,
Sean

 

Placement is talked about a LOT here, but you are right, you need to have one BEFORE your first cat (or only cat), and one after it.

 

I've seen the heather element go bad a few times,especially on turboed car
try to keep the sensor about 18'' from the turbo or install it right behind the engine that will keep a bit of heat away from it

 

i put my 02 sensor right where the stocker would go on my header and then after the cat but i still get a CEL. i think when i change out flexpipes i'm going to try to move that 02 sensor to in the flexpipe and see if that makes a diffrence.