Hi, amongst my fleet of Samurais, I have a 1990 Sidekick that I use as a winter vehicle. I bought it several years ago from a fellow soldier for $500. It's probably the best $500 I've ever spent!  The soldier's wife had bought it new and she said it had been driven all over the US and had been a great vehicle. She was sad to let it go, but they had too many vehicles for a upcoming move. 

Anyways, as I was driving home last night and the CEL came on at 70,000 miles.  Does the Sidekick CEL come on every 30k miles?  If so, this would mean that the vehicle has 270k miles correct?

I know that it's at least 170k miles, but it would be more outstanding if it had 270k miles. It still runs great, starts everytime, and cruises at 70mph no problem.

I believe it comes on every 60k.  If you take the speaker off on the drivers side there should be a switch behind it, just flip that and it will turn off.

if that doesnt work you could check the codes

Here's a link to the kick-fix page dealing with the "nag switch"
http://www.kick-fix.com/CEL/NAG-Lamp.html

kick-fix's site is a life/wallet saver
matt