Up here in Ontario we have a drive clean program to have the car smog tested before renewal tags are issued. I've had few problems with my S and it passed it's first test fine. Thinking I would be smart, I reset the ECU (there were no codes, but still, I went ahead). The car failed because the testing computer couldn't find most the sensors. So now I need to drive it, have the sensors etc. come back online, then take it back (I'll have to pay a small fee for a retest). Sometimes, when you're trying to be extra 'smart' ... you're being extra stupid.
Live and learn - hopefully you don't run into the same issue!