I've said before I was going to get my O2 sensor replaced because my gas mileage is horrible. I went to the dealership to see if they even had one so they could replace it, and they did and it was about $75. First, is this too much?? I didn't think it would be that high. And second, has anyone else had theirs replaced by a shop, if so how much do you think it would be with parts & labor? I have a feeling this isn't going to be as easy on my wallet as I thought. Thanks!

Probably about $40 thru gmpartsdirect. A 3-wire connector for 94, I think, and a crescent wrench.

Sound better? I can get you the part number later tonight. Maybe I'll start bringing my books to work with me!

I just did mine a little bit ago. It cost me $34.07 from gmpartsdirect. I then bouth an O2 socket from my local parts store so I copuld do it myself. The socket only costs a couple bucks. It is really as easy as using a socket set to pull the old and install the new. There is only a single wiring harness between the O2 and the cars wireing. If you can do you own plugs I would deffinaetly suggest doing this one yourself and save come $$$.

It'* very easy. I use a special O2 socket, and three long socket extensions.

Sounds much better than $75 PLUS labor! Though I have no experience with this type of replacement. I've basically done the 180 stat so far and that'* it? About how long do you think it would take for me being a beginner in all? Is the O2 sensor visible from under the car or is it hard to reach? Sorry, I have no clue about some of this stuff. Need to learn though before I get my next bonne! Any directions for this in techinfo (I'll check after I post this). Thanks.

The O2 is in the downpipe, right behind the rear exhaust manifold. Access from the top, just below the Strut bar. The connector should by tied to the rear plug wire bracket. Just follow the harness up from the sensor. Looks kinda like a spark plug. The new sensor should already have anti-sieze on the threads, and don't touch the lower part of the sensor that goes into the exhaust. You don't want any finger grease or boogers on it.

It should take you 5 minutes, even with a crescent wrench. Just do it cold. If it won't break loose, run the car for a minute to warm up the manifold a bit, and try again. If your thermostat was a 10 on the beginner scale, this is about a 2 on the same scale! Very easy.

If the 02 sensor is out, or bad, does it have to throw a Check Engine light. Cause when I got the car the dealer replaced it for free, and he had like 3 other Bonny'* there so he could have taken one off of there thus, the O2 sensor still sucks, or something.

My understanding is that they will only throw a code if it goes out completely, such as in a disconnected harness. The O2 sensor will detiriorate over time slowly giving more inacurate readings. The O2 sensor has some middle ground between good and bad.

I wouldn't put it past a dealer to use one they just happened to have sitting around, or they might not have even done it at all. Depends on the dealer.Some try to unload cars on people and some do actually strive for customer service.

I have about 109,000 miles and doubt it was ever changed. I used to get about 275miles to the tank, which is still horrible, but lately I've been getting 220-230 a tank. Once the O2 goes bad, does mileage usually go down pretty quickly? It seemed to go pretty quickly with mine. Either way I'm going to replace it. Anyone have any guesses as to how much improvement in mileage I'd see with a new O2 sensor?
Thanks for the info, I look forward to saving my money!

94, that'* exactly what happened to me. Within 30 days, my mileage dropped by about 5. The Bosch only got 3 back for me, and it smelled BAD. I ditched it two months later for a stock AC Delco, and the mileage went back up and no stinky!

It can go in big chunks, or gradually, or both.