I was wondering if anyone can help me out. When i got my car it already had the whole exhaust redone with aftermarket stuff. I have a 97 camaro ss and i was wondering if it originally came with 2 cats or 1 and if it is supposed to have 2 O2 sensors or 4. When i was looking on the net for replacment O2 part #'s it keept showing sensors for upstream and downstream but i only see 2 on my car. Any help would be great thanks!

 

originally your car had two cats, and 4 oxygen sensors. Two sensors before the cats and two after the cats. It is likely that if you had a custom exhaust set up made that the rear O2's are no longer on your car. The Oxygen sensors you have in now are (or should be) before the cats. it is likely that whoever oened that car and did the exhaust put in a pair of O2 simms where the rear O2's should go...the rear O2's are not used for running the car like the fronts are, so often times they are taken out when aftermarket exhaust is put on.

 

FWIW...also, if you are replacing the front O2s...the p/n is 25312184 from gmpartsdirect.com, price is ~$38...front O2's have a flat 4-pin connector.

 

Would the rear O2's be needed to stay leagel with emissions or will the sims do the same? Will the sims allow the computer to adjust the air/fuel?