Realistically, at what point is an O2 sensor not useable anymore? Right now, it is not reading, through no fault of its own. My whole exhaust system is junk, I have all the parts to replace the entire system (just short of the manifold). I am sadly paying someone to do it this time, as I no longer enjoy lying in fozen, or nearly forzen puddles/mud/gravel driveways to do such work as I no longer have a garage to work in. My exhaust has been in such a condition that there is not enough back pressure for the O2 sensor to function properly. The biggest question for me is will this cause a need to replace this as well? or, if it was in good condition prior to this, will it still be useable once the new exhaust system is in place?
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-Kilted Chaos Manager-

It may be working. Unhook the single lead in the engine compartment, (firewall, passenger side) and check its voltage output. It should bounce between .1 and .9 volts.
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

"The biggest question for me is will this cause a need to replace this as well?"

By itself, no. A number of things kill an O2 sensor but lack of back-pressure is not one of them.

"if it was in good condition prior to this, will it still be useable once the new exhaust system is in place?"

Maybe...but did you test it prior? How long has it been in this condition? It the sensor portion exposed to road salt, oil and grime?

Bo not be penny wise and pound foolish. If you do not know if it is function and you do not want to get under the car in the near future, just have it replaced when the exhaust is replaced.

I have been driving like this for about a month now, the O2 sensor is not being exposed to the elements any more than if the exhaust system were intact, just everything past the cat is in pieces. I am going on the assumption of this (not enough pressure for the sensor to function) due to my "check engine" light coming on shortly after my exhaust system went to pieces. They are not all that hard to change if it does not work after the exhaust system replacement I just didnt know if it not functioning would harm it in any way.

Thanks

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-Kilted Chaos Manager-