The Nissan Path

How long of a job is it for the O2 sensor to be replaced? I have an 2002 pathfinder if that makes a difference.
The service engine light came on the other day. So I took it up to autozone to have them scan for a code so I knew if I needed to get to the shop immediately and how long I should expect it to be in the shop for (my nearest nissan dealer is an hour away, so I sort of need to make a day of most trips there). Anyway, the code came back as an O2 sensor. Common enough. I made an appt. at the dealer and they confirmed what autozone told me. However, they said that the sensor is $230.00 and that it's a 2-2.5 hour job which would cost about another $250.00. that puts it very close to $500.00. I about crapped my pants. It isn't covered under my warranty so I declined the repair because I knew that I could get the sensor for around $80.00. And there is a good mechanic which I trust in my city. So Even if I get hit with a $250.00 labor charge, I'm still saving $150.00 by not having the dealer fix the issue. Anyway, can anyone tell me what kind of time I'm looking at for the labor?
Thanks in advance.

I have 01 Pathfinder which I think is similar to 02. I think it depends which O2 sensor is bad. I think there are 4 of them. 2 of them are kind of inside engine compartment and are hard to get to and I didn't change them. For $500 I would give it a try.

The other 2 are right under the truck plugged into exhaust pipe (kind of look like spark plugs with long wires - look at the autozone picture). I did change both of them in my garage and it wasn't hard. Routing the cable back took some time as you have to route it back to the harness which is under the hood and the space is tight. You can also buy O2 sensor in Autozone for 1/2 the price.

The code that you pulled should indicate which o2 sensor is bad. If you are mechanically inclined I would give it a shot.

Thanks! I did buy the part from autozone. And I had Midas put it in while I was at work one day. both the part and labor this was was cheaper than either the part OR the labor separately at the dealer. Amazing how much more dealers charge.
I would have tried doing it myself, but I was having issues with finding out which one was bad. I had 3 different answers from three different sources (both online and people). And I figured that I better leave this one up to the professionals