How do I take my 2003 gmc Yukon out of limp mode

Just drove out of the mountain only
about a hour drive then into the city
for about 30 min when
I got off the freeway with no warning
my car just die would not restart .... It
did not overheat and my battery is still
good . Some reason I belive it went
into limp mode.... How do I fix this I try
to undo the battery did not work ... I
test it for codes none came up ....
What do I do