There was an episode of "Wheeler Dealers" a few months ago which showed a refurbishment of an XK8 which had a continuing problem with the Limp-home mode. It was quite interesting to see how Ed China rectified it, which was exactly as Trevor suggested. In the end it was the sensor which was not that expensive, but the diagnosis was the bit that could be. Slightly away from topic the engine malfunction light on my S Type came on again yesterday, and the engine scanner which arrived on Friday came into use. Quite easy to use, although I was unable to get the connection correct, and it was too cold to keep trying! However, I must have frightened it as the light went off when I started the engine again.