Kbar

I have a 04 F-150 with a 4.6L. It has 64,000 km's on the engine and I had to replace both heads on it last week. Now I have the security light coming on when I am driving which as you know kills the engine. I have tried both keys to see if it is the chip but it doesn't make a difference.
Does anyone have a suggestion?
Or should my truck spontaneously catch fire!