My daughter has a 2009 Yaris with the automated manual box. She usually changes gear with paddleshift to avoid the well documented jerky progress with these transmissions.

Last week the engine management light came on and she took it to the Huddersfield Toyota dealer who plugged it into their diagnostics and announced that the auto change function was not working and thought a new box at £1300 or so was the answer. They reset the light, which came back on the next day. But box is still working as normal, in either manual or auto mode.

Could it just be a sensor problem? If not could we reasonably expect a goodwill contribution from Toyota if a new box is needed? Car has only done 30k and all but one service has been with a Toyota dealer.