Overdrive is flashing

[mafloc78]

Hi, I need a little bit help. Sometimes when I driving blinking the Overdrive. Not every time. Before 3 weeks was the car on the mechanic. He was cleaning the transmission with some liquid and changed the filter and put new oil inside. Before never was flashing.

Have somebody any ideas of this problem?

 

[bdmaash]

slipping transmission, just a matter of time before the rebuild.
Speaking from experience. (maybe it was a simple fix but I paid $2k since I don't know anything about transmissions, that's after I tried swapping out the valve body).