XC70 Transmission problem

[AndyL]

I can't find any PO800
Anyway, it seems you probably have a bad valvebody solonoid(s)
At this point (high mileage you may as well install a rebuilt valvebody and you may be OK after that.

Thanks for replying

I had the wrong code - it was P0811 and not P0800. The problem still exists however, since the oil change it seems better.

The car often stands for several days - is it possible something was sticking and its loosening up?