Don't know if this will work for you, but I just had the same problem on a 98 XC. My check engine light came on, My OBD reader reported the barometric sensor. I re-set the light and it came on again after a few days. At that time I removed the sensor and cleaned it, top and bottom. A large opening on the bottom and what looked to me like a very small opening on the top. Anyway, after two weeks I am still without any check engine lights. It's worth a try.

I seem to remember the barometric pressure sensor costing in the neighborhood of $150.00, and it takes all of about...hmmm...5 minutes, tops. This sensor also plays into the climate control system, so therefore, it can affect your air conditioning. Now that it's about to be October that is most likely less of a concern. If funds are super tight, keep checking your codes so that you are aware of new ones should they occur. (I hear AutoZone reads them for free). If you can spring for the part, do it yourself. It sits sorta on the inside of the passenger side fender, right up top, right up front.

Hope this helps,

Chris