W639 Vito 115 - Air Temperature Value -40

[ChrisCUK]

Hi All,

First time poster but been using this forum for a long time as its full of useful information.

I am the proud owner of a W639 115 Vito and ever since i have owned it (3 years) it has always had a really rich diesel smell coming from the exhaust. For ages i just put this down to "its one of those things, being an old diesel". Recently I plugged in an OBD2 reader and found that the MAP sensor was reading a static 100kpa. Change this MAP sensor and it started to fluctuate as expected (in relation to revs). When reading through the other live data i noticed that there was an value called AAC (Ambient Air Temperature) that read -40C constantly. My dash reads the external temperature fine (around 15.6 C today) and when i unplug the ambient temperature sensor under the bumper it it vanishes from the dash which leads me to believing that the ambient temp sensor is fine.

Does anyone know of any other sensors which could affect this AAC OBD2 value? It strikes me that the rich exhaust smell is from slight over-fuelling due to incorrect sensor values but of course I could be wrong. Ive checked and i dont have a MAF sensor not sure if i should or not (i get conflicting views depending on where i ask).

Any help would be much appreciated.

TIA

 

[m80]

There is a temperature sensor on the air route near the valve body, I think.
Yes there should be a MAF and pretty sure that has a temp sensor also.

 

[ChrisCUK]

Did some double checking on WIS and EPC and my Van doesnt seem to specify a MAF sensor. I have checked the temperature sensor on the air intake (right under the intake manifold) and that seems to be working fine. The van works fine and doesnt throw up any error messages so wonder if im looking for something thats no there.

Does anyone else have a rich exhaust smell from their 115 Vito 639 (Pre DPF)?

 

[MattEVans]

Hi, i do have the same smell and I have the fault codes of MAF and IAT, did you locate the temp sensor as I cant locate it? its not the ambient one, rather the intake one.

Did you fix it?

 

[alecmascot]

He was a hit and run member......
Start your own thread.