Condensation
 

2 years ago, I noticed some light condensation in the clear portion of the rear driver's side inner light lens (2010MY D3) and on closer inspection there was a hairline crack in the lens. Sorted, so I thought. Went back to the dealers and got them to replace the cracked lens under warranty. The new lens now has even worse condensation in this clear portion, to the point there are large droplets in there.

I went up to the highlands last year in May and when parked at the top of the Cairngorms, noticed that it had all gone (pressure drop with temp rise maybe??). It was clear again. This lasted until about October or November of last year and then it started getting worse again and now the droplets are back. No other rear lens does this on my car.

Is there an issue with this lens inside (broken seal/crack, etc) or is there any kind of removable cover or plate that may not have been fitted correctly (are there actually any incandescent bulbs in there at all?) or is there any way I can dry it out or get some silica gel in there without trashing it? Anyone got any pics of the back of one? Bit bad on what was an £80k+ car. :Confused::(

Just found a photo on eBay of the back of one of the lights and also an exploded diagram of the same cluster in the parts catalog, so the white panel comes off and there is a pair of incandescent bulbs in there and a seal to keep it dry. Time to take this apart and dry it out and make sure the seal is sealing properly. Maybe it wasn't installed correctly at the dealers.

It will be interesting to see what you will find there Lee.
Also, don't forget that most of the ''single glazed'' things will condensate to some point.
I bought brand new OEM FL tail lights and they so condensate a tiny bit depends on outside temp and water temp, I think, but not badly. If there is any water inside that wont obviously help with unusual amount of condensation.

If you can take the light off and keep them at home overnight in warm condition and put some Silica gel packs inside then I'm sure you'll be able to get rid off all the moisture from inside and then all whats left is to find where the water comes from and make a new good seal

I've stuffed some small sachets of silica gel behind the trim in the boot. I'll report back on how it affects the rear lamps soon.

Almost no effect, unfortunately. Any other ideas, other than removing the cluster and waving a hairdryer at it?

On that light there is a small plastic cap, is there room to run a hose to a small container full of silca gel so the light has a expansion vessel but a dry atmosphere?

Ironically, I was just about to do mine this weekend, but whilst out yesterday, noticed that it had all gone and was bone dry... +++ must have something to do with the overall ambient temperature. I noticed that it has still been in double figures even at night for the last week or three.

I put big packs of silica gel behind the covers on all my lights front and rear.
Also cleaned the seals with a cotton bud and silicone spray.
I seem to recall this was not possible on the facelift rear lights but I fitted them in the dark in a rush so can't remember but they were more like sealed units IIRC. It seems to work but in very code weather I can get the odd bit but not like before.