I am really surprised at the lack of help you are recieving here.

First of all. If it says "Bank 1", that would logically be interpreted as the bank with cylinder number 1. (and 3 and 5). One thing you can try is to disconnect the front O2 sensor on Bank 1 and then go have your codes checked again. (Autozone does it for free) If you dont have another code, you have found the correct sensor.

Secondly, $250 for an O2 sensor is rediculous. When you pay for an OEM type sensor, you are getting a sensor that has the exact same plugs as the original sensor so that it plugs right in. The non-OEM sensors work well, you will just need to splice the wires together. One more thing, some O2 sensors have heaters and some don't. Just make sure that the new one matches. A couple good places to get O2 sensors www.sparkplugs.com or www.rockauto.com. I see on sparkplugs.com they have an OE style O2 Denso sensor for $76. Sounds good to me.

One last thing. It is often very difficult to get the sensor out due to the corrosion. Get yourself some PB blaster" (next to the WD 40 at your local Autozone) and let it soak overnight on the O2 sensors threads. It still might not come off, so try warming up the pipe a bit by running the engine for a few seconds. Unfortunately, sometimes they can be nearly impossible to remove.

Good luck and let us know how it goes. <img src="/forums/images/graemlins/cheers.gif" alt="" />