my 05 mustang gt had the same exact thing. they had to replace the fuel sender unit. there was sulfur build up on the sensors to the unit. They tried techron the first time and I even began to just exclusively use chevron with techron after that...however that did not work..so when I brought it back to them they replaced the fuel sender unit....has not done it since...

 

My GT is still giving the error, albeit sporadically. I've all but given up having it fixed as it isn't causing drivability issues. It'll go a month without the error then do it three times in a week.

 

The car is nearly five years old, 54k on the clock and it's still throwing the error sporadically. Does anyone know what may be causing this annoyance?