I have had my check enine light on and diagnostic said that I
needed an o2 sensor. I ordered one from internet then called
a mechanic to check on how much it costs to install. He asked
which one needed replacing because there was two. Is that
right? HOw would I know which needed replacing?

 

theres only 1

 

just one. you can do it yourself if you have a jack and a 17mm wrench. that's all it takes..

and maybe some needlenose pliers to remove the clips from the chassis.. but you can get by without it.

 

make sure your exhaust is warm before trying to loosen out the o2 sensor. or heat up the nut with a propane torch. they get pretty seized in there and if you heat things up it'll be easier to do.

 

Well, I wouldn't trust my car to that mechanic, because there's only one. Also remember, there's a reason I might've gone bad. The front Y-pipes in 3rd gens tend to rust out given the age of our cars. With my experience, a rust hole in the Y-pipe caused the o2 sensor to pick up to much air, so the EFI would run the engine rich, which caused burned gas to go out the exhaust...and screwed up the o2 sensor.

just my .02

 

The engine light is still on. The diagnostic prior to replacement said the O2 was the problem but the light remains on. Should I get another diagnostic run or is there something I need to do to re-set the computer?

I am trying to get this thing throught the Cal. emissions test and they won't
even run it with the engine light on.

My fear is that the entire exhaust system is shot because of the years on the East Coast. How much should I expect to pay for a new exhaust system?

 

You need to reset the ECM.

 

Here's how:

To reset the computer what you do is either:

1. turn your key to the on position (but don't turn the engine on), turn the diagnostics screw all of the way clockwise, let the two lights flash 4 times, turn the screw all of the way counterclockwise, turn the key to the off position and wait about 5-10 seconds.

2. Unplug the battery for 24 hours.

 

How do I reset the ECM?

 

I don't mean to sound ignorant but where is the diagnostic screw?

 

Remove the kick panel to the left of the passengers feet. This will expose the ECM. You should be able to see the "diagnostic" screw then. On mine, it's underneath a clear sheet of plastic that has to lifted up.

 

Really???? I usually do your step #1 but with the car running and be done with it. i'm confuse now!

 

Re-read carefully.

 

Her is why I had to change my O2 sensor:

Sometimes I think my car is too low, but then 2 min go by and I am over it.

 

ohhhh, i did not see that word "either"....got it...me bad.

 

No problem! Welcome to the forum!

 

Great info here. I'm off to try to change my 02 sensor myself.

 

I went thru 3 exhausts and one O2 sensor over almost 6 years that I own the car and the O2 sensors never got seized. The one on the car looks as rusted as was the one, replaced in 2001, but it can be removed without much trouble. Maybe it's because every time it had to be removed, it was after some driving...