Emissions Maintenance Timer and O2 sensor

Hey everyone. The other day, my emissions maintenace light came on. It is my understanding that there is a smallish timer box that sits underneath on the drivers side that controls this light.... unforunately, I can't find it!! Can anyone give me a better idea location-wise where it is?

Also, what O2 sensor would you recommend? I was looking on Autozone.com and they had 2 different ones. One was Bosch ($50) and the other was Bosch Universal ($65). What are the differences between the two?

Thanks.

Well, I replaced the O2 sensor with the $50 Bosch. I'm now getting about 2 mpg more than I was before. That's nice since I drive 100 miles a day.

But what about that darn "MAINT REQ" light on my dash? My Haynes repair manual says that the emission maintenance timer, which controls the light, needs to be replaced as they claim it cannot be reset. Well, while I was visiting my folks over the holiday, I happened to go to a Chrysler parts and repair shop (owned by a dealership in town) on a completely unrelated matter concerning my sister's broken keyless entry remote. I asked the guy behind the counter about how much a new emissions maintenance timer would cost, and he asked me why I needed a new one. I told him that I needed to replace the one I had since my light had gone on. He then told me that he had only replaced 1 in the years he had worked there, and it was only because the timer had been damaged due to fire. He said that any chrysler dealership can use a "scanner" to reset my timer for me.

Is this true? If so, how much do you think they would charge me to do it? I doesn't seem like any work at all, especially since I already went and changed the O2 sensor on my own.

I did it myself, i just found the Emissions Maintenance Timer in my Jeep Wrangler 1991, Its a clear brownish box with small plastics gears on the inside "like a clock" its factory set it for 2750 hrs. you just need to look at that box in the back and remove the sticker to gain access to a small opening where is the activated switch , and with a small screwdriver move that switch from the top of that small gear to the border of the gear where its a guide for the switch. disconect the + terminal from the battery and touch the negative terminal with it the reconect the + terminal and thats it.

Most owners just remove the bulb from its socket once the Jeep gets over 100K miles instead of replacing the timer module.

Mike