I have an 05 screw with the 5.4 with an x-cal III running troyers 89 performance tune. My truck has been shutting off and the display on the dash says "engine fail safe mode". It has done this 4 times in the last 2 months. My problem is it doesn"t throw any codes when it shuts off and does this. I stop the truck put in park turn the key off for a few seconds and then just restart. So far it's been restarting and running fine. How do you figure out whats causing this with no codes? It has good oil pressure and the temp is fine, basically all fluid levels are fine and the guages read fine when it does it. I am stumped due to if I take it to the garage they wont be able to read any codes that my x-cal III can't read correct?

 

Oh, there's a continuous code present. It's just that not every scan tool or programmer out there can see it.