You can get that message for a number of reasons. The DCS system's messages are generic. They don't tell you the problem. They just display a reason.
I've gotten the no TIU for poor signal at the track for example. The TIU was on and getting power.
Engine reset is for resetting the engine to either full feature reset or a factory reset that erases any data you entered.
Engine recover is only for finding an engine that got a bad address (out of the normal range) during a procedure.