O2 question

[surfer92]

My left O2 shows 100 - 200 on Datamaster and I getting a lean O2 error msg, is this a sign of a bad O2 or a exhaust leak? Car is a 93 w/headers and Bosch 13190 heated O2's n one last thing, does the ECM use both O2's to set A/F mixture or just one and if 1, then which one?

[rodj]

Originally Posted by surfer92

My left O2 shows 100 - 200 on ?

Is that the Mv reading?
If so it is not working , should constantly swing through whole range >900Mv

[surfer93]

But it would stay low, if there was a exhaust leak?

[Rohn]

How old is sensor? If old I would just replace it. When I had header flange to EXT leak it still swung or swinged. whatever.