FIXED 08 535i - 9C55 code - fog sensor fail

TheFixer

Sergeant
Aug 16, 2020
493
352
0
Tennessee
Ride
2008 535i
I have a bad fog sensor. Causing hot air to blow through defroster when ac is blowing cold through vents.

Is it incorporated with the rain sensor or separate? Went to bmw parts and they can't find a 'fog' sensor.

Thanks for the help.
 

TheFixer

Sergeant
Aug 16, 2020
493
352
0
Tennessee
Ride
2008 535i
I think they are the same thing.
Probably. Google searches I'm doing lean that way.

It's confusing because the fault says 'ifogger' sensor. Not rain sensor. If they are one in the same it's odd too as the rain sensor works fine for the auto wipers.

If it didn't cause the hot air issue I wouldn't care to replace it at all.
 

TheFixer

Sergeant
Aug 16, 2020
493
352
0
Tennessee
Ride
2008 535i
Ok.... it's called the condensation sensor and it's separate from the rain sensor.

Ordered a new one from fcpeuro.com Only 146 dollars....ugh. At least it's lifetime from them.

All good.
 

TheFixer

Sergeant
Aug 16, 2020
493
352
0
Tennessee
Ride
2008 535i
Nice. So it installs in the same space as the rain sensor area?
Just underneath it. You can actually see the condensation sensor from outside the widow. The rain sensor is a rectangular box thing hidden above it. All tucked away in that plastic housing around the rear view mirror.
 

TheFixer

Sergeant
Aug 16, 2020
493
352
0
Tennessee
Ride
2008 535i
FYI. The condensation sensor is the bottom sensor. I'm glad there's a mounting clip on my windshield for it. From what I saw most are stick on.

Also, this did fix the hot air blowing from the defroster and footwells while the ac was blowing cold through the main vents.

Blows cold everywhere again.
 

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kd7iwp

New Member
Dec 19, 2020
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FYI. The condensation sensor is the bottom sensor. I'm glad there's a mounting clip on my windshield for it. From what I saw most are stick on.

Also, this did fix the hot air blowing from the defroster and footwells while the ac was blowing cold through the main vents.

Blows cold everywhere again.
I'm happy to hear someone else chime in that they have the clip-on sensor as well. RealOEM shows me that I should have a bonded sensor for my 2009 535 touring but mine has a clip. I've got the same error so will pick up this sensor.
 

Stipa

New Member
Nov 10, 2023
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Where that fog sensor is located? I don't have error but windows fogs up in damp weather.
 

Arthur635d

New Member
Oct 10, 2022
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Where that fog sensor is located? I don't have error but windows fogs up in damp weather.
Hi Stipa, the fog or condensation sensor is located behind the plastic cover the surrounds the rear view mirror electrics. JFYI most older BMW's fog up at some stage. My 2009 E63 does it, and like you I don't have any errors pertaining to the HVAC system. The fog sensor is part of this system. I have also just replaced my AUC sensor which has improved things a little, but it still fogs up. Mine clears up real quick now, under a minute usually. It's all about interior vs exterior temperature differences. I have discovered the most likely cause in my case and possibly older BM's could be door/sunroof seals etc. I hope some of the above helps with your issues
 

Stipa

New Member
Nov 10, 2023
7
1
0
Hi Stipa, the fog or condensation sensor is located behind the plastic cover the surrounds the rear view mirror electrics. JFYI most older BMW's fog up at some stage. My 2009 E63 does it, and like you I don't have any errors pertaining to the HVAC system. The fog sensor is part of this system. I have also just replaced my AUC sensor which has improved things a little, but it still fogs up. Mine clears up real quick now, under a minute usually. It's all about interior vs exterior temperature differences. I have discovered the most likely cause in my case and possibly older BM's could be door/sunroof seals etc. I hope some of the above helps with your issues
Thanks! Mine AUC sensor is dead from day I purchased car ~10y ago, but fogging problem started only ~2 years ago. Strange thing is that windows start fogging up in a middle of a ride, I have manually activate front windscreen defrost. Few days ago guys replaced front windscreen and showed where sensor is located. If problem will repeat itself I will try to replace fog sensor.
 

Arthur635d

New Member
Oct 10, 2022
5
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Thanks! Mine AUC sensor is dead from day I purchased car ~10y ago, but fogging problem started only ~2 years ago. Strange thing is that windows start fogging up in a middle of a ride, I have manually activate front windscreen defrost. Few days ago guys replaced front windscreen and showed where sensor is located. If problem will repeat itself I will try to replace fog sensor.
Hum, if you have just had your windscreen replaced that could have something to do with it. Unlikely but it could. Also in my old E39 and E60 I used to put the aircon on cold which cleared the screens on both. Maybe worth a try, although I'm not sure what it would prove, it worked for me.