I wonder does anyone know if the rear window heater comes on automatically at low temperatures? I know it seams a silly question but, now its colder up here, mine (2012 model) seems to switch on and off on its own. there is no indication at the switch. I know it comes on when you start at low temperatures but the warning lights on the switch illuminate. The only reason I think it comes on is the area adjacent to the heater wires tend to become more obvious in the spray for a while then disappear and cycle.
Of course it could be a trick of the mind.
Hugh

There are vents in the back on the sides behind the parcel shelf IIRC, so it could be that warm air is circulating itself against the rear screen - just a thought.

Don't think it is capable of switching itself on/off to be honest. ON THE WAY: BMW F21 M140i
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Have the same on mine but then it does show it is switched on. I will monitor this in the next few days

Terry

Mine does it too, as Hugh says it's more obvious when the window has spray on it, on mine it almost seems like it's working on low power as it does not clear/dry the window completely iit just clears around the wires. 12MY RRS Orkney Grey HSE Lux
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Exactly right Essexfarmer it seems to be at a lower power since I have tried it actually ON and the effect seems faster. There is nothing I can find in the handbook. I suppose it could be thermal conduction in the metal wire but it seems stronger than that. Well to me at least.
Thanks for the thoughts.
Hugh