Is there still any way that the dealer can tell that the ECU has been tampered with? Are any of the stored electronic messages (warning lights, maintenance light, etc) effected by changing the ECU?

I think the ECU registers something like a power failure on the ECU.
IMO, I think sometimes it's not worth the hassle of changing the ECU/chip just for an oil change. Then again, that's just me.

Cris

It shows a power off fault. There is no way to tell what caused it (like you disconnected the battery to work on the stereo, etc). It will go away after 30 start according to Todd at AWE.

Chris