How do I?

[thermal]

I'm not accustomed to Accord configurations but I know that I can count on you guys/gals here.

So here it goes:
My girl has a 94 Accord LX Wagon..... yes a wagon .... dang... and I love it! It's not modified. Completely stock and I intend to keep it that way unless she tells me to turbo it and I'll be more than happy to make it happen . A CEL has been on for a while now and she was told that it was the O2 sensor. I'm okay with that, but I just dont trust the person who diagnosed the code. I want to do it myself. My question is, where is the ECU located on these cars? Does it have the same blue clip where I can tamper with to count the CEL blink like on civics and tegs? If so, where is it?

Another issue is the alternator/ps belt squeaking like crazy sometimes. The belt feels loose. Where do I adjust the tension on this belt? I can figure it out by looking at it but it's too freaking cold outside. A picture would definitely help if possible. The moderators, since a few of them drives an accord, should jump in on this matter. Anybody else's inputs will be appreciated on my behalf. Thanks.....