Service Interval System - Can it be recoded?

[thrillcat]

Having a strange behavior with my SIS. I had the oil changed a couple months ago, about 1000 miles. At the time, the Service Interval System was reset.

It's already down to the yellow and telling me to think about having my oil changed again... It's done the same thing twice now, after both oil changes I've had done.

I had it changed right away when I purchased it, because I didn't know how long it had been and the SIS was indicating a need. I took it to a quickie place because it was the only place open. Used 100% synthetic but didn't plan on going the full time before having it changed again. About 2000 miles later, the SIS was indicating a need again, and I just had my indy change it out while it was in getting some other things taken care of. Now it's already yellow again...

Any ideas? Could a previous owner have re-coded the SIS? Is it simply faulty?