Have had my truck display the wrench light on dash several times now and go into fail safe mode which is a fraction of the power. I can turn off engine and it goes off and will be fine for days. Heard the gas pedal assy might be causing this and ideas ??

 

Moved to the 6.0L Powerstroke Diesel forum.

 

It could mean any number of things. There will be stored codes that the dealer can read that will tell you.

 

There are alot of reasons for that to happen. Have the codes read and post them.

 

was no code stored.

 

This could easily be an overboost, or more commonly an indication of a plugged oil cooler (EOT-ECT is greater than 15 degrees). Not all code readers will read these codes. Either take it in to get the codes read, or find a way to read the ECT and EOT. A scangaugeII will read these temps (coolant and oil).