I have a S type 05 model 2.7 D. It appears that the pre heater is emitting large amounts of smoke on start up. This only started recently. If car is standing this is then blown into car via ventilation system. Any one any idea?

They all do that. 

Pull the fuse out in the under bonnet fuse box, think it's number 4, which will stop it. 

Ive not used mine for at least 2 1/2 years. 

Had the same webasto unit in a merc sprinter I had a few years ago and that smoked it's head off too.

was told it needed a service kit to sort out. 

Pulling the fuse is cheaper. 

My pre-heater did the same and I had it cleaned out. Solved the problem :)

Personally, I find them to be a very efficient way to get the engine up to temperature quickly in low ambient temperatures.

I have the same problem, its not just a bit of smoke. i think i will have mine looked at, pulled the fuse but takes too long to warm engine up.

Press recirculate button?

Thanks for all your posts. I will use recirculate button for now. Perhaps pull fuse in spring.

The pre heater only works if the outside temperature is below 5* and the climate is switched on.