Hi Dave, I have also seen A/C fault codes on Rovers with no A/C fitted and I did wonder about that. It may not be that which is causing the fan to run. I do not have any great knowledge of the way a ecu works but it is definately that which is the problem. ATP told me that it was not responding to the cts so that was why a new one was supplied. Incidentaly, this vehicle has a central locking fault that I havn't looked into (I only have an Autodata wiring diagram for Rover 25). Is there anyway that the immobiliser could be causing the config problem?