the second O2 sensor?

[Gman94]

I have a 95 prizm/corolla it has 2 O2 sensors one on the header and one after the cat but I dont have an OBD2 plug cause I guess this is the year before they put in the plug, but I was just wondering if I really need it cause im going to be replacing the stock exhaust from the downpipe all the way back and need to know if I have to custom fit that in or if I can just unplug it and run off the one at the header?

[Bitter]

yes you need it, i suspect that you might have a cali spec corolla. there were 3 iterations of 7th gen.

fed spec
cali spec
obd2 cali spec

fed spec has one sensor in the exhaust manifold and a cat
cali spec has 2, one in the manifold and one after the cat and i tihnk has 2 cats (one attached to the manifold, its a big bulge)
obd2 has 3 sensors i think, one before the precat, one after the precat and one after the main cat. i know less about the cali spec and the obd2 since mine is a 93 fedspec. iirc the cali and obd2 also have EGR and do not have adjustable timing.


as for the exhaust, just get a bung welded in and put that sensor in. a bung shouldnt cost more than $50 to get it installed by a shop. if you're decatting then you'll need to use the antifouler trick which can be readily found on google.

[Gman94]

I just have one cat and i didnt have that manifold with the big bulge on it it was a regular manifold until i changed it to headers.