RR Auto Gearbox Temp Warning

Hi,

Occasionally, this evil little light offends my otherwise lilly RR dashboard.

There is no burning smell, and the auto trans fluid doesnt look or feel hot. The input pipe to the heat exchanger is hotter than the output, so that would seem to be ok.

It only seems to come on at low varying speeds, not along the motorway at a steady 70.

Is there any other way to tell if the light is talking porkies?

Thanks for any advice.

Mike Freeman