Possibly 2 minutes at the very most. I was doing smog on the fly after trying to get some super shady aftermarket wiring solved, turns out something they did is tied into my electrical for the fans that caused them to not turn on (Yeah I know, thats [email protected]&%!). Pulled it off the second i saw it hot and cooled down for an hour. Within 5 minutes it was back to normal temps though.How long was it pegged for? If you get it moving in open air fairly soon the temp will start to drop. Or pull up to a water hose and spray the radiator to cool the engine.
Did you get the fan problem fixed? Keep an eye on your coolant level and temps for a while. If it wasn't too long or too severe you're probably ok. The ECM does have an added fail-safe in that it deactivates fuel delivery to alternating cylinders to provide emergency cooling.