97 XK8 Transmission no shift cold

I just acquired 97 XK8 from a friend. Only 13K miles and none over last three years. Only issue is car will not shift from first gear cold, Gives “gear fault” code. Trusted mechanics say it just needs driving. It will correct itself after slow driving for a few minutes and drive great after approximately 1/2 mile travel. Is there a reset/reprogram mode for this transmission?? It works well after correcting itself.

Thanks
dennis

Since it sat for so long, I would suggest you have the transmission flushed and refilled.