Electric Thermostat Explained: Audi A4 8E

Hello!

Brauche mal eine techn. Sure, here is the translation of the text from German to English:

"Explanation."

My neighbor has an Audi A4, model 8E, manufactured in 2002, with a 2.0 gasoline engine. The engine code is ALT.

Has the electric radiator fan been running at high speed for 10 seconds after engine start (cold start) during the recent cold weather?
The car didn't reach its normal operating temperature, and the heating system wasn't producing properly hot air. The temperature gauge also wasn't displaying anything accurate.

Okay, so first I read all the error codes, and in the engine control unit, it showed an error for sensor G62, which is the dual coolant temperature sensor, indicating a short circuit to positive voltage, with an implausible signal that appears intermittently.

"Because it was the simplest and cheapest option, and there didn't appear to be anything obviously wrong with the wiring, I replaced the G 62."

The problem with the constantly running cooler fan has been fixed. The temperature display is working again as well. So far, so good.

I bought it at the , and I also looked at what else might be suitable at Edeka.
The problem with the excessively low coolant temperature persists.
As far as I understand, the car has an electric thermostat.
A single unit costs €95 net. It has a 2-pin connection for a cable.

Before I replace it just in case, I'd like to understand how it works first.

Is this a standard bimetallic thermostat, as has been common for about 70 years, but with just a temperature sensor inside?

Or, is it actually a fully electric one, with a servo motor?

I didn't even know something like that existed until today.

It's best to see it directly:

Hi!
Thank you, great.
I didn't know that kind of thing existed, especially with an old car like that.

Are there any experiences with that?
Should I just replace the part, or would it be more helpful to check other things first?
The told me, in any case, that they sell thermostats more often.

Hello Steffen,

Machs neu, die Dinger sind wirklich anfällig, oft verziehen sich die Kunststoffteile im Inneren und auch das Gehäuse ganz leicht. DSometimes, that's enough.
that the function is limited and it no longer opens or closes properly.

The manufacturer for the original part (VW/AUDI: 06B121111K) is Behr/Mahle.

Behr also distributes this product in the aftermarket as well, but at a lower price .
The part number for the ALT is TM3100 from Behr.
Price-wise, it then comes to approximately €45 because it doesn't have the logo of the vehicle manufacturer on it.

Regards,
Mpire

Hello!

I fixed the car today.
Everything is working again.
The neighbor bought the thermostat himself; it's a part from Mahle and cost around €40.
It was quite a job taking the intake manifold off, with all those strange clamps that I don't really have the right pliers for.
I think I should buy something for that too.

Well, anyway, we disassembled the defective thermostat to see exactly what was broken.

Okay, so it's a standard thermostat at first glance, and looking at the electrical components, it seems like there's an additional mechanism in one of the cylinders that adjusts the preload. So, something that expands and is electrically controlled is definitely included.

The cause of the failure was that the two plastic clips, made of cheap black plastic, which hold the thermostat in place, broke off. As a result, the thermostat was only loosely held within the housing.