FWIW, I had this happen after going through a car wash.
It started flashing after it came out of the wash. Code was P0713-Trans Fluid Temp high input. Since it was only about 50 degrees that day, and I had only driven a couple miles to the car wash, I'm expecting some water shorted something.
The light stopped flashing after a day of drying out, and I have cleared the code. So far so good. And damn it looks good when clean.
'98 SVT Mustang Cobra
2002 SVT Focus