# Hymer external temperature sensor



## DaveJM (Dec 29, 2008)

Hi,

The external temperature sensor on my 820 reads 80 degrees all the time - that is centigrade!!

So I am looking to find the sensor to see if the wiring is frayed etc, but can I find it.

I called that well know Hymer dealer and the technician I eventually spoke to very helpfully said and I quote "it could be anyware underneath - there is no standard place to fit them"!!

The Merc chassis has a gauge also but that is under the front bumper, actually under the radiator.

Anyone any thoughts?


David


----------



## GEMMY (Jun 19, 2006)

I'm luckier than you, mine reads +60c all the time, even at a true -20c :lol: Its not important, I just ignore it.

tony


----------



## cabby (May 14, 2005)

If and when you do find it, please post its location in case anyone else needs it in the future.

cabby


----------



## Carper (Aug 15, 2007)

DaveJM said:


> Hi,
> 
> The external temperature sensor on my 820 reads 80 degrees all the time - that is centigrade!!
> 
> ...


 Mine used to read -20.....and i assume it still does

Doug


----------



## apxc15 (Dec 1, 2007)

Mine says it's -25c even in the summer heat of Spain.

Pete 8)


----------



## DaveJM (Dec 29, 2008)

Seems this is a common problem!!

Anyway I called Hymer in Germany and they told me it is underneath next to the steps. It looks like a piece of cable about 5 cms long and 5mm in diameter. So I had a look and sure enough there it is. 

The problem is the sensor is not easily detachable at that point so will probably get it fixed when I'm down at Hymer HQ in Germany next month.

David


----------



## Brock (Jun 14, 2005)

Mine seems to work fine. It's probably not accurate but its close enough. At least I know when it is cold and when it is warm. No idea where it is though.


----------



## jim_5388 (7 mo ago)

I have a Hymer B544 2013.
The sensor is hanging in the space behind the front fog light on the drivers side (Mine is a Right Hand Drive).
There is a coil in there not sure what that is for? but the sensor is hanging below that.
Not sure how I change it, but at least I've found it.


----------



## trek (May 1, 2005)

Rather an old thread but anyway 
The control panel tends to be above the habitation door and therefore the external temp senor will be found underneath the floor somewhere around the door as the cable from panel to sensor may only be 2 metres , look for an electrical tube crimp connector that is screwed into underside of floor with the wire coming out heading upto control panel It’s made by Shaudt they are expensive to buy but it’s just a thermistor and can be repaired cheaply you just need to get the correct thermistor .. it’s been covered before perhaps on this or other forums so try searching for thermistor ?


----------



## jim_5388 (7 mo ago)

The external temperature sensor is for the dash board temperature display and has an effect on the A/C temperature and fan control.
It does not go to the Hymer control panel, I assume it goes to the main vehicle wiring harness under the bonnet.
The sensor lives in one of the rear view mirrors on a van or coach built motorhome, but an A class uses it’s own mirrors rather than the Fiat ones so they hide the sensor somewhere else.
Even Hymer went much help in finding it. I saw a one line in a conversation on line and hey presto it is in the void behind the front fog lights on my Hymer B544. If I could follow the wire back to a connector that would be ideal.
I think I need to post some pictures once I get a replacement and fix this.
There are losts of posts on this, but not many fixes or sensor part numbers.
Teach me to by an A class.


----------



## jiwawa (Jun 22, 2007)

At least I'll know where to find it if/when mine goes! Maybe when you get sorted Jim you could put the photos on a new thread with an appropriate title? Might make it easier for the next poor soul to find.


----------

