W222 Moisture in Head Lights
Before I left up north a couple weeks we had some rain storms and I noticed the right one was fogging, the sun seemed to dry it out. I would have them check the O ring seals though where the bulbs go in behind the headlight.
1) They are no solution in fact they accelerate the destruction of your headlight control unit, by leaking their contents right into the control unit which causes corrosion of the printed circuit board and total destruction of the unit.
2) MOST surprising to me was the following: If you have gelpacks in place and don’t see any moisture in the headlight afterwards it doesn’t mean its not actively doing damage.
In my case gelpacks were installed and I never saw moisture afterwards in one particular headlight. 2 Years later with no fogging what so ever the control unit failed, on inspection the gel packs had expanded and set hard and burst leaking the residue into the control unit. See photo below, please note I have cut open the pack in this photo, when it was in place the bags were bursted.
3) There's no seal on inner surface of the control unit (see photo below), so moisture with gel pack residue can freely enter the unit to destroy the PCB.
If you have gelpacks installed make sure you replace or inspect them at least every six months, other wise it inevitable they will leak into your control unit.
1) They are no solution in fact they accelerate the destruction of your headlight control unit, by leaking their contents right into the control unit which causes corrosion of the printed circuit board and total destruction of the unit.
2) MOST surprising to me was the following: If you have gelpacks in place and don’t see any moisture in the headlight afterwards it doesn’t mean its not actively doing damage.
In my case gelpacks were installed and I never saw moisture afterwards in one particular headlight. 2 Years later with no fogging what so ever the control unit failed, on inspection the gel packs had expanded and set hard and burst leaking the residue into the control unit. See photo below, please note I have cut open the pack in this photo, when it was in place the bags were bursted.
3) There's no seal on inner surface of the control unit (see photo below), so moisture with gel pack residue can freely enter the unit to destroy the PCB.
If you have gelpacks installed make sure you replace or inspect them at least every six months, other wise it inevitable they will leak into your control unit.
- Added two Grey Nitto vent caps to what looks like vents on the bottom of the assembly.
- Added another two Grey Nitto vent caps near the upper control unit.
- Used high quality silicone to seal around the entire perimeter of the headlight assembly where the lens cover meets the main assembly.
I also plan to remove all the control units now, and use a suitable PCB spray coating to waterproof the PCB, then reinstall the metal backing plate and seal with high quality silicone. This will prevent water damage in the future I hope.
If moisture returns then using duct tape I’ll be sealing over the existing breathable membrane as installed by Mercedes so as to allow the venting via the Nitto caps only.
Ill be using the desiccant gel packs to clear the moisture and removing within a few weeks, as we all know at this stage they don’t offer a long term solution, and result in more damage.
Most important of all I’d like to acknowledge I’ve been in regular contact with a member of this thread (username: GKH), who first steered me in the direction of this possible fix, thanks for all the help it much appreciated.
Here’s hoping we can find a long term fix for this issue.
Last edited by sclass350d; Nov 6, 2020 at 04:07 AM.
Since I last replied with the above post moisture did re appear with four nitto caps installed.
I removed the headlight again removed the Mercedes breathable membrane and installed a nitto cap in its place, I also added one more nitto cap. So in total I have 6 nitro caps and no Mercedes membrane.
I also sealed both control units on the inside with silicone to.prevent damage to the electronics on the inside.
Finally using a high quality 3M tape I taped up where the lens meets the assembly and the top of the assembly covering over the light adjustment screws.
I've used the car at night time for 3 hours in damp conditions with a temperature of 8 degrees Celsius, no moisture has appeared so far after.
So initial results look promising!
Heres some images:
Last edited by sclass350d; Dec 2, 2020 at 05:05 AM.
https://mbworld.org/forums/e-class-w...densation.html
I've since re-installed new gel packs in both headlights which has resolved (temporarily) the moisture issue, so looks like I'll be replacing the gel packs on the passenger side every 12 months and every 6-7 months on the driver side.
I have a right hand driver car, so the passenger side headlight control unit can be removed easily, gel packs replaced in under 5 mins. However driver side take a little more effort but doesnt require the bumper removal or headlight removal, heres the steps, in total took me 20 mins:
* disconnect electrical connection to coolant bottle, and lift it to forward.
* Unscrew two bolts which hold the windscreen washer bottle in place.
* Remove retaining clip on inside of fender lining which pushes into the washer bottle.
* Lift window washer bottle up and out of the way.
* Now the driver side control unit can be removed and gelpacks installed.
I still have the control units sealed with silicone so Im hoping moisture cant damage these in the future, as soon as I seen moisture ill keep replacing the gel packs, far from ideal but 30 mins work in total it better than looking at mess the condensation makes and a reoccurring repair bill every 12 months.
Last edited by sclass350d; Dec 8, 2020 at 01:45 PM.
The Best of Mercedes & AMG




If the previous headlamp versions burned off the water vapor with the heat from the headlamps, what do you think about sealing the vents on the new LED lamps that only get warm during use? It would seem that there would only be a small amount of water vapor available inside the headlamp if it is sealed, or a vacuum seal could eliminate the possibility of vapor forming on the inside.
Perhaps the headlamp vents are in the wrong locations.
I am also wondering that if the above technique is not feasible, how about a adding a micro heating element or small hi-temp bulb inside the headlamp assembly that is automatically turned on and off via a temperature- and humidity-controlled switch?
If these two ideas were feasible, I would think that the Mercedes engineers would have already tried them.
https://www.gore.com/resources/white...isture-removal
1) They are no solution in fact they accelerate the destruction of your headlight control unit, by leaking their contents right into the control unit which causes corrosion of the printed circuit board and total destruction of the unit.
2) MOST surprising to me was the following: If you have gelpacks in place and don’t see any moisture in the headlight afterwards it doesn’t mean its not actively doing damage.
In my case gelpacks were installed and I never saw moisture afterwards in one particular headlight. 2 Years later with no fogging what so ever the control unit failed, on inspection the gel packs had expanded and set hard and burst leaking the residue into the control unit. See photo below, please note I have cut open the pack in this photo, when it was in place the bags were bursted.
3) There's no seal on inner surface of the control unit (see photo below), so moisture with gel pack residue can freely enter the unit to destroy the PCB.
If you have gelpacks installed make sure you replace or inspect them at least every six months, other wise it inevitable they will leak into your control unit.
You are 100% correct. It is exactly what happen to me. They actually tried to blame me since I hand wash the car often. It was exactly the Gel Pac. I kept every photo and email from the 1st intrusion of moisture in the headlight, enough to condense and drip down the inside of the light. If I did not keep my well documented notes and photos, it would have made it more difficult to prove the case. The total repair was close to 4K on them. They replaced both headlight assemblies. If you have night vision, those lights are a hefty price. I would strongly suggest for the DIY'er, if they have time and patients to waterproof the the electronic assemblies. Moisture WILL get into them with the Gel Pac over time. My gel Pac;s leaked out and went directly into the electronics.
How about we collect all the VIN numbers of cars/customers with this issue and take a single complaint to Germany showing it multiple customers.... I'd be willing to coordinate this if others are interested.
I had this issue on my w213 and my headlight blew. After a very expensive replacement by Mercedes in 2020, it started to fog again, so at the next service i got them to put a cap on the back of both the headlights with the silica gel. That solved my problem but a couple of months later same again!!
So after getting tired of replacing gels i got a breather vent and plastic nut (about £2), took the gel out, drilled a 12mm hole in the cap and put the breather vent and nut on. After two and a half months no issues...however the other light with the gel was soaking with water!!! So changed that as well today
Hope that's the last of my condensation problems

Here is the vent https://www.electricalcounter.co.uk/...IP68/951066499
Here is the nut https://www.electricalcounter.co.uk/...ant+/203926719
I had this issue on my w213 and my headlight blew. After a very expensive replacement by Mercedes in 2020, it started to fog again, so at the next service i got them to put a cap on the back of both the headlights with the silica gel. That solved my problem but a couple of months later same again!!
So after getting tired of replacing gels i got a breather vent and plastic nut (about £2), took the gel out, drilled a 12mm hole in the cap and put the breather vent and nut on. After two and a half months no issues...however the other light with the gel was soaking with water!!! So changed that as well today
Hope that's the last of my condensation problems

Here is the vent https://www.electricalcounter.co.uk/...IP68/951066499
Here is the nut https://www.electricalcounter.co.uk/...ant+/203926719
How about we collect all the VIN numbers of cars/customers with this issue and take a single complaint to Germany showing it multiple customers.... I'd be willing to coordinate this if others are interested.
I would love join the complaint group. Better Businesses Bureau should also be notified!




I would love join the complaint group. Better Businesses Bureau should also be notified!
1) They are no solution in fact they accelerate the destruction of your headlight control unit, by leaking their contents right into the control unit which causes corrosion of the printed circuit board and total destruction of the unit.
2) MOST surprising to me was the following: If you have gelpacks in place and don’t see any moisture in the headlight afterwards it doesn’t mean its not actively doing damage.
In my case gelpacks were installed and I never saw moisture afterwards in one particular headlight. 2 Years later with no fogging what so ever the control unit failed, on inspection the gel packs had expanded and set hard and burst leaking the residue into the control unit. See photo below, please note I have cut open the pack in this photo, when it was in place the bags were bursted.
3) There's no seal on inner surface of the control unit (see photo below), so moisture with gel pack residue can freely enter the unit to destroy the PCB.
If you have gelpacks installed make sure you replace or inspect them at least every six months, other wise it inevitable they will leak into your control unit.
So for the last 3 years I swap out the gel packs every 12 months [every December], never once have I seen a moisture build up since. 30 euro for the gel pack well worth it to avoid this nightmare.
Could have mentioned this already in here, but I can replace the gel packs on both headlight in 30 mins. I do it without removing either headlight or bumper.
on one side its a little more complicated I have to move the coolant and window washer tanks.




So for the last 3 years I swap out the gel packs every 12 months [every December], never once have I seen a moisture build up since. 30 euro for the gel pack well worth it to avoid this nightmare.
Could have mentioned this already in here, but I can replace the gel packs on both headlight in 30 mins. I do it without removing either headlight or bumper.
on one side its a little more complicated I have to move the coolant and window washer tanks.
Regards
Kevin
I decided to do some research and found the module on eBay from a trusted seller in the US for $58. I ordered it on Monday, it arrived today, and I decided to install it even though it's 17 degrees outside. Everything is working again as it should with no errors!
For those of you who have a blown light or module, replace just the module and do not let MB tell you otherwise. It's their design flaw that caused the condensation and their fix is a band aid that will destroy the module. They won't own up to it and make matters worse by recommending a $4000 headlight replacement. I'm still unsure if I should put the packets back in, but I guess I'll see how bad the condensation is before I make my decision.
Link to the module below:
New Headlight LED Ballast Voltage Regulator Module for Mercedes # A2228700789 | eBay
I decided to do some research and found the module on eBay from a trusted seller in the US for $58. I ordered it on Monday, it arrived today, and I decided to install it even though it's 17 degrees outside. Everything is working again as it should with no errors!
For those of you who have a blown light or module, replace just the module and do not let MB tell you otherwise. It's their design flaw that caused the condensation and their fix is a band aid that will destroy the module. They won't own up to it and make matters worse by recommending a $4000 headlight replacement. I'm still unsure if I should put the packets back in, but I guess I'll see how bad the condensation is before I make my decision.
Link to the module below:
New Headlight LED Ballast Voltage Regulator Module for Mercedes # A2228700789 | eBay
IMHO what is criminal is that Mercedes doesn't offer this module.
Last edited by MBNUT1; Feb 3, 2023 at 07:29 PM.






