I have a bad left 02 sensor which is giving a super rich signal, it does not fluctuate from 1190 at all. this is causing a nasty stumble but as soon as the car throws the 02 code with the SES light on the car runs nice and smooth. I was wondering if i just disconnected the left 02 would the car keep the 02 code on with the SES and run smooth(er)?

 

I think it's running smooth because the engine goes back into open loop, when it isn't using your O2's. Faults in the system prevent the computer from putting the car back into closed loop - You "could" disconnect the O2, but the car will not go into closed loop. I think the only real side effects of not going closed loop are, your fans will probably stay on 100% of the time, your gas mileage will probably suck because the computer purposely makes the car run rich, and you'll take a performance hit. Maybe someone else can chime in and give you more exact details - I'm still learning myself. I bought a bosch O2 from Auto Zone for around $45, you can always call Jason Cromer (www.samtaylor.com - parts, get his # there) and order an AC delco one.. but as far as I've seen and read, Bosch O2's from autozone work fine. I do recommend you replace both of them at the same time, though.

 

Get a new one. The PCM uses the O2s for fuel management.