Warning light problem on 406

Check the relays next to the fan units behind the front grill, under a long plastic cover. Also adjacent to these are the resistors. Remove these (one screw) and check the connections for corrosion and the windings for breaks (common). Note they are colour coded, grey and black. Any corrosion found try and clean up, but may need to renew the component. Also check the plugs to the components for burning and/or corrosion. Clean up as necessary or if really bad the loom is available and easyish to change.

Thanks Nigel as soon as it stops raining I'll give it a try Cheers Steve

Try the connectors round the Bitron sensor if you have one. My Citroen does similar things intermittently which seem to be cured by fiddling with the connectors