Have a 2007 525EFI...Changing my IAC valve today and on some other forums people talked about "putting the computer in a maintenance mode" before changing it??
Looks too easy to just pull the plug and put the hex bolts back in? Am I missing something?
Thanks in advance.

Nope. Just make sure everything is turned off. Apart from that, disconnect / reconnect the plug and bolt back on. Make sure you replace the gasket. And just a word of caution, those hex bolts are a little soft, so be careful loosening and tightening or you will spin them on the inside..

I seem to remember that there was a reset procedure fo the IAC in my Merc manual for my 502 MPI .I believe it said to switch key on fo ten seconds then off ten seconds then start engine.It may not be the same for the 525 EFI . I am not positive and I lent my manual to a friend so I can not check.

^^^^ correct with the MEFI / and that set up for the IAC - 2001 ECM / PCM is not the same. Also for a IAC to work correctly it needs a good seal - so a new gasket is important plus do not torque your IAC so that it warps from the install. Also the mounting surface needs to be clean and free of any of the old gasket material, plus not warped either.

the magic for longevity with the IAC's is make sure your flame arrestor is always clean - they hate belt dust - Also if your app has the IAC muffler change or least clean it once a year min. Also clean the cavity in and leading to the IAC.

Also long term IAC muffler use can self digest themselves in the cavity that it sit in. That's another reason to change to brand new every year, Depending on the app some do not have IAC Mufflers and some have one version and some have another version. They cost about 3 bucks not worth leaving old ones in or cleaning them. Change them period with a new one. its that simple.