My octy mk1 rear window demister doesn't seem to fully demist anymore.

It's definately working because it starts to clear but acts as though I've turned it off too early.

Any ideas?

Most heated rear screens are switched on and off via a relay. The switch on the dash switches the relay on, and the relay then provides a live supply to one side of the heated screen. The other side of the screen goes to earth.

So it's back to basics here. Switch on the HRW and see if it has a feed and yet not working. If it isn't working then check to make sure it has a good earth. If you don't have a feed check the HRW switch and relay.......

Thanks railroad- will try