Rep Power: 0

So for the last 2 weeks we've been getting terribad gas mileage. Yesterday, the check engine light came on. We stop at Autozone, and the guy says P0135, 02 sensor. He turns it off, it comes back on again immediately. He tells us a new one will be $160, and the car has 3 of them.

I searched the forum some, and found a few people who have replaced this. None were specific to the '04 LX that I saw, so before I spend money i don't have screwing this up, I thought I'd ask some questions.

1.) The site has a list of all the codes. On that list, p0135 indicates it's in Bank 1 Sensor 1. This is going to be in the engine, under the manifold, correct?

2.) It might just be loose, and need to be reseated, right? Before I go out and buy one, I should check that? This is unlikely as I understand it, though, it's a really hot place and it's probably dead - right?

3.) Are there any special tools I'm going to need, other then apparently a special wrench from Autozone?

4.) Is $160 really the cheapest I can get it? I looked on Majestic Honda but didn't see one.

5.) Is this something I can do? I've replaced the bulbs for the headlights, the battery, a tire, and the CD player, and that's really all I know so far.

Thank you very much for the advice. I'm nervous but hopeful that I can fix this myself.