This light comes on sometimes not always when I have been driving for about 20 minutes. Fluid is good and car drives great. What could be making this light come on? Thie light doesn't always come on and is not on when I first begin to drive the car. I just bought this car used with 55k miles so I don't know if this was already happening or not. Also it is scheduled for transmission maintenance at 60K miles. Could that be why light is coming on?