just wondering my O2 sensor has been through a lotta crap. If my cat is dead I'm willing to bet my O2 sensor isn't so good either. It still worx but I have no clue how well it worx.

I know if it was bad the computer would pick it up or I'd get crappy mileage or something. But from my smog printout it shows I have no O2 in my tailpipe meaning I'm running rich. Could it be possible that the O2 sensor still worx but is kinda half assed working?

has ne1 ever encounter that their car worx well but they weren't passing smog because the O2 sensor was making the mixture a little rich.

o2 sensors just break without any warning. I had one go bad after 30k. It sucks because they are kinda expensive but realy easy to replace.

i once had one that broke before it was ever created!

They are a very picky sensor, and can easily go bad. Especially if you are running nice and rich and burn up the O2 sensor. I had a bad O2 made the car idle like crap, and ECU never kicked a code for it.



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The best way to tell is watch the voltage. if its not cycling at idle, as in going from ~.1 - ~.9 then its most likely bad. It should start cycling about 5-10 min after a cold start. From day 1 your O2 is going to collect deposits and slowly go bad. It may still look like its working right, but its slightly off.

I think the deposits make it see less lack of o2 and sending a leaner signal to the ecu. The ecu will then up the duty cycle a little bit to compensate and you will have higher emissions.

hmm ok looks like I'm replacing the O2 sensor also at least that NTK one I hear about from Nopi isn't so bad. Does ne1 know if the replacement they sell will plug and play into a 95? Mine has a kinda square rectangular connector.

thanx for the replies I never knew it was that fragile, haha I always assume if the car seems to run fine then there's nothing wrong but in the end I"m wrong :P

Originally posted by Michael_97RS
They are a very picky sensor, and can easily go bad. Especially if you are running nice and rich and burn up the O2 sensor. I had a bad O2 made the car idle like crap, and ECU never kicked a code for it.

What did you do to fix it, just replace it? Cause I think my car idle's (I think) like shit compared to when I was non turbo but that might just be normal idle or and newly turbocharged non-turbo car. my computer gave me a code as follows = 12,21,55 I dunno what 12 means but 21 ment in my Hayes Manual (Problem with upstream Oxygen sensor signal circuit. Sensor voltage to computer not fluctuating. So I replaced the one in the downpipe but still seems to run like crap and I think it is still putting out that code. Should it just blink 55 if everything is good? Someone please inform me. Thanks in advance.

There realy is no fix for it except replacement.