Condensation in car headlight?

[Mercedes2018]

I’ve noticed condensation inside my driver side headlight on my 2015 Mercedes. I’ve heard this can be due to the outside temperature being colder than the inside hence why the condensation appears. However, I’ve never had this issue before and it’s only just started on one of my headlights. I have used a hairdryer on the outside of the headlight in order to remove the condensation and it all went away. Within minutes it started to build up again. So the next day I tried the same thing with the hair dryer and it all went away only for it to come back.

Just to confirm there’s no damage, chips or any loose fittings to the headlight to what I can see. Even after lifting the bonnet it all looks sealed and fine.

Now I would like to know why is this issue occurring and why after heating it up and getting rid of it, it keeps coming back?

I’ve attached a picture for reference. Any help would be much appreciated, thank you.

[steveo3002]

hair drying is just getting the moisture into the air inside the lamp....need to then vent it out

i suspect its got a small leak...try a packet of those silica gel granules that come with new trainers in the rear cap

[swisstoni]

There are often tiny holes in light enclosures to let vapour out. Perhaps these are blocked?

[Mercedes2018]

steveo3002 said:

hair drying is just getting the moisture into the air inside the lamp....need to then vent it out

i suspect its got a small leak...try a packet of those silica gel granules that come with new trainers in the rear cap

These are LED headlights, as far as I’m aware these are sealed tight with no access points unless the headlight is taken apart?

[steveo3002]

Mercedes2018 said:

These are LED headlights, as far as I’m aware these are sealed tight with no access points unless the headlight is taken apart?

not sure ..might get expensive then

[Mercedes2018]

steveo3002 said:

not sure ..might get expensive then

After doing some research apparently Mercedes say it’s normal and it’s even written in the manual. Hard to believe but will get this checked by a garage and Mercedes

[Mercedes2018]

swisstoni said:

There are often tiny holes in light enclosures to let vapour out. Perhaps these are blocked?

I’ve had a look and cannot find any, I’m unsure this is different with LED lights as they don’t generate much heat

[TarquinMX5]

MBs, amongst others, are prone to this. One of ours has LED headlights and does occasionally have condensation inside, particularly if very wet/humid, even if driven with headlights on: LEDs don't produce enough heat to remove it.

As you say, it's covered in the handbook - that's not to say that I agree that it should happen.

[Jaguar99]

LED headlights tend not to be sealed units and will mist up sometimes

This is normal expected (and normally in the handbook)

[Mercedes2018]

TarquinMX5 said:

MBs, amongst others, are prone to this. One of ours has LED headlights and does occasionally have condensation inside, particularly if very wet/humid, even if driven with headlights on: LEDs don't produce enough heat to remove it.

As you say, it's covered in the handbook - that's not to say that I agree that it should happen.

This is the first time I’ve experienced this and I’ve had my car for 3 years. I wouldn’t be concerned if it was both of the headlights but because it’s only 1 I’m slightly concerned thinking if there’s a loose seal this might be the cause. I’m keeping an eye on it and which get it checked by dealers however, as it states in the handbook it’s normal I’m assuming they’ll just state this.

Another reason why I’m concerned is if enough condensation builds up which converts into water, maybe this could damage the headlights LED completely.

[Mercedes2018]

Jaguar99 said:

LED headlights tend not to be sealed units and will mist up sometimes

This is normal expected (and normally in the handbook)

Attached is an image is an example of the model of my headlight looks like from the back. It looks pretty much sealed to me and no areas to open to ventilate it?

I was looking to open up a cap somewhere in order to let fresh air in however as it’s installed to my car it’s hard to see if there’s any. I’ve sourced this picture from eBay, it’s the exact headlight unit which I’ve got.

[TarquinMX5]

Mercedes2018 said:

TarquinMX5 said:

MBs, amongst others, are prone to this. One of ours has LED headlights and does occasionally have condensation inside, particularly if very wet/humid, even if driven with headlights on: LEDs don't produce enough heat to remove it.

As you say, it's covered in the handbook - that's not to say that I agree that it should happen.

This is the first time I’ve experienced this and I’ve had my car for 3 years. I wouldn’t be concerned if it was both of the headlights but because it’s only 1 I’m slightly concerned thinking if there’s a loose seal this might be the cause. I’m keeping an eye on it and which get it checked by dealers however, as it states in the handbook it’s normal I’m assuming they’ll just state this.

Another reason why I’m concerned is if enough condensation builds up which converts into water, maybe this could damage the headlights LED completely.

Agree, and there have been some posts on MB forums (fora?) about this but no real solutions that I recall. I don't think it's only an issue with MB as I've seen similar with Audi, for example.

[quinny100]

Both my W205 C Class and S213 E Class have had small amounts of condensation in the lights sporadically, but nowhere near as much as shown in your pictures - just a light misting across the bottom of the lamp and usually present in both lamps to a similar degree.

IIRC Mercedes say any “normal” misting should disappear after a few minutes of the lights being on.

Yours looks like it’s letting water in.

[Mercedes2018]

TarquinMX5 said:

MBs, amongst others, are prone to this. One of ours has LED headlights and does occasionally have condensation inside, particularly if very wet/humid, even if driven with headlights on: LEDs don't produce enough heat to remove it.

As you say, it's covered in the handbook - that's not to say that I agree that it should happen.

Update: I’ve been to my Mercedes dealership and they’ve checked it over. His mentioned there’s no access points and it’s a sealed headlight unit. In this case they will have to remove the bumper, take out the headlight and put it the silica gel packs to remove condensation and seal the headlight up again. Waiting for the parts to arrive so will give an update next week.

[swisstoni]

And when the silica gel is saturated?

[Mercedes2018]

swisstoni said:

And when the silica gel is saturated?

I guess I’ll just take another trip to the dealer. I did mention this but they just said “we’ll sort it out don’t worry”

[ro250]

We get this occasionally on our 2016 Mercedes. I researched it and it's normal as LED lights don't give off heat so if you look very carefully on the glass you will probably see a pinhole which is there to manage the condensation.

[Mercedes2018]

ro250 said:

We get this occasionally on our 2016 Mercedes. I researched it and it's normal as LED lights don't give off heat so if you look very carefully on the glass you will probably see a pinhole which is there to manage the condensation.

How long does this condensation normally stay for?

Mine appeared after driving in heavy rain. It’s been about 5 days and it’s gotten better but it still there.

[Mercedes2018]

Here’s an update of what it looks like after 5 days of dry weather