limp-home mode

[vietvet]

daughter-in-law has 2006 mustang V-6. for some reason car will go into the limp-home mode ( guess that is what it is ) wrench shows up on panel. pull car over, restart and then everything is fine. might not do it again for month, week or maybe the next day. have taken it to dealer but could not find anything wrong, of course everything was cleared on restart. she works nights and is hard to get to shop when this happens. have installed new plugs and fuel filter with no help. any help would really be appreciated. lost and dont know where to look for problem.

[Blue)(Fusion]

This is usually an indication of a faulty sensor that is important to the engine's running safely. When in limp-home-mode, the PCM limits the RPMs and speed so damage won't occur to the engine.

I know of one case where a bad battery caused this issue. Somehow the battery wasn't "cleaning" the voltage from the alternator which made the PCM think some or all of the sensors were faulty therefore stayed in limp-home-mode. Once it was diagnosed as a bad battery, the issue never returned.

And if a garage is not nearby when this happens again, take it to an auto parts store. They usually have scanners that can read the codes. Go inside and tell them you have this problem, they'll hook up the scanner and read any codes and, if they have a good enough scanner, read freeze frame data. That can help narrow down the problem.