Warning re-set problem

I recently had a warning to tell me the washer level was low. I filled up the main tank (the one in the boot inside the spare wheel), and checked the stronger mix washer in the engine comp. I switched on and a pump automatically filled the main tank in the engine comp. from the reservoir in the back.
However, I can't get rid of the warning on the computer screen. Everytime I start up and every time I switch off it is there.

Any suggestions?
Thanks
Peter

Thanks for the suggestions, I'll let you know
Peter

Disconnecting the battery for 30 minutes stopped the warning coming on. However, I ran the washer until it emptied to test the sensor. I now have the same problem, so perhaps it is the sensor.

Unfortunately, I now get a front fog-light warning after driving a minute or two, but there is nothing obvious wrong with the fog lights.

I need to get this investigated. In the meantime, if this combination means anything to anyone, I'd appreciate any suggestions

Peter

New sensor cost £17. Now I can start up and switch of in peace.