I went to start my truck and it was very choppy.... Engine not running smooth like I'm used to. Currently the weather is cold but only around approx. 36 degrees Fahrenheit. No snow or rain and only sitting there for approx. 2 hrs. While I was in the barbershop. As I'm pulling off I'm noticing that I have reduced power and really notice something was wrong. I checked to make sure i was in normal drive, and the checked the information screen and it said " engine fail safe mode". I continued driving to my house. When I got home I pushed the reset button/ the word went away and my regular screen popes back up. Turned car off.......no problem....nothing on the message screen/ no choppy engine nothing. However I still has not driven it yet. I'm in here typing you to find out what the heck happen to my truck and is this going to happen again?

Patiently waiting for a reply.

Truck was running perfectly fine when parked for a winter. Got it out later in the fall of 2012 and when started driving, truck started to shake really bad and "Engine Fail Safe Mode" message came up. Plugged a code reader into it. Was telling me it was either the throttle positioning sensor or the throttle actuator. Replaced the throttle positioning sensor and problem was still there. Next to replace the throttle actuator, need to replace entire throttle body. Once I replaced that, I read that I needed to get my computer re-flashed by a Ford dealer and it should clear the issue. Got that done and as soon as I drove off the lot thinking it was all going to be good. Truck started shaking again and the "Engine Fail Safe Mode" came back on. Have no idea what to do now!! Pretty stressed and not sure what to do.

Prevent FAIL SAFE MODE: When changing the battery on ford f-150 keep 12 volts to truck by plugging battery charger to cigarette lighter. Otherwise, like my truck went into fail safe mode after replacing battery. The check engine light came on too giving two different codes.

In this mode the truck is not drivable.

HERE IS THE FIX : remove both cables from (took me several times about two days) Also get a code reader and CLEAR THE CODE before buying ANYTHING.

After replacing cables to battery over and over, then clearing the check engine light codes, truck computer was reset and no more problems.

I wish Ford would tell us this on the manual to keep 12v to it when replacing battery.