Dangerell

Hi,

I have a problem with the thermostat on my Audi A8L 2011 3.0 TDI 250HP (engine CDTA), in vcds i see this error "Thermostat for cylinder head" - open circuit. (the water temperature its ok and stable, never went more then 90)

I went to audi, i bought a new one... it comes also with the oil filter housing.... my mechanic replaced it... we cleared the errors and the error is still there.

After we replaced also the battery as it was also planed to do so, being too used... even the start stop was not working because of it.... so after, the error disappeared... but after arriving home (like 30 km driving) it reappeared.

Now the error is still showing up, and even if i clear it ... it comes back.

Can someone tell me what to check, maybe someone already had this problem, its wires related... as the thermostat its brand new OEM?

I attached a photo with the error (old photo but error is the same) and one with the part (just informative as i bought it oem but i forgot to take photos before installing).

Thank you.

laurent0613

Salut,

Open circuit doesn't necessarily mean your part is broken.
It might be a cut wire or a bad/loose contact on the connector...

Dangerell

Hi, thanks.
I tried unplugging 1 by 1 the sensors near the thermostat and in one of them i did not gave any new error, for the rest i got new errors... meaning they work... and stop when disconnected.

Should i focus on replacing that one that didn't gave any extra error in vcds when i removed it (was just the main one shown) or its surely wire / connectors related?

Thanks.

laurent0613

You have indeed 3 coolant temperature senders.
1 on the middle top
2 in front.

I would yes also focus on this particular one as your main unit is was already replaced.

Dangerell

Hi,

I went last night to my mechanic to recheck... we took them out again 1 by 1, the ones from left are ok... they pop new errors... putting them back... errors go away.

We removed also the main plug from the thermostat and we got a new error something regarding "thermostat mapping", placed it back error disappeared.

We went to the right side ... just behind the roll or how its called.. (see photo), we removed it and there is no new error... so it means that should be the problem.... the sensor or the connector / plug.

The problem is that its very tight i cannot find the reference, i went with those photos to audi and they said its difficult to find it.

Is there someone here that can help me with the reference of that sensor / plug / connector or to tell me what sensor is that so i can do a deep search in etka ?

Thank you!

Dangerell

I found in etka a thermostat in the same region, but it looks different from what i see in my photos... probably its something else that i need. :/

I attached a photo.

laurent0613

Indeed, this is the most difficult one to access as you need to remove the belt and pulley...

It should look more like this:

laurent0613

079919523 temperature sensor coolant temperature sender

Dangerell

Thank you very much!

I will go tomorrow to audi to order it and i will come back with info after i change it.

Dangerell

Sorry if i ask you too much,

Can you please tell me also the reference of the connector / wire or how its called that plugs in to the sensor (maybe a repair kit .. to weld it to the wires.. or idk.. something similar) ? As from what i see in my photo... its also pretty damanged, like this i replace them both.

Thank you billion time!

Something like this, photo is just as an example... as i don't know the exact part code/design (maybe its exactly this one... LOL).



I think is one of those from 6 to 9.