So, here I am at 4pm on a Saturday afternoon and my Check Engine Light comes on. Neighbor suggested I take it to AutoZone to check the codes (Apparently there was a rush today on that problem!). It checked out to be the Transmission Fluid Temperature Sensor. It had just gone over 90k and I was going to take it in for servicing anyway. So far I'm hearing that I can wait until Tuesday with no problem, but I thought I'd check in with the experts here. Oh, 2007 Hyundai Sonata. Thanks!