check engine alert flashes on and off. what could be problem? on 2003 Cadillac DeVille

alert came on solid and went off then came on and off and flashes. engine runs rough at idle. could this be serious? having it checked tomorrow. anything to be alarmed about?

by in Spicer, MN on October 17, 2012
1 answer
ANSWER by , October 18, 2012
scan test it for codes