I think you have a solenoid sticking. What is likely happening is as the temperature rises, the plunger and the coil expands and the clearance disappears, freezing the solenoid in the current position. THIS DOES NOT mean you need a full transmission rebuild, just replacement of that solenoid.
Get it to a dealer or a competent independent mechanic who can run diagnostics on it. Get to the problem before it gets worse, it may simply be a failed sensor.
14th Apr 2016, 18:46
I think you have a solenoid sticking. What is likely happening is as the temperature rises, the plunger and the coil expands and the clearance disappears, freezing the solenoid in the current position. THIS DOES NOT mean you need a full transmission rebuild, just replacement of that solenoid.