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View Full Version : Question Audi A4 B8 2009 2.0 TDI 170hp - Second thermostat problem ( coolant under 90° )


Robert06
19-01-2021, 11:53 PM
Hello! I've recently bought my A4 and it has a problem, coolant temp hardly reaches 700​C when I drive around for some time, and then when I stop for a few minutes, it goes down close to 500​. As I've read a lot around forums and Facebook groups, I've come to the conclusion that the problem might be in a second thermostat on a hose ( See nr. 23 in the photo below ). For my model, do you know what the code for that thermostat is? I need to order it because the service I went in can't seem to find it and basically said that they're gonna change it if and when I will manage to get one. I found this: 03L 122 157 M ( this is the hose from nr. 23 ), and I wanted to know if it work on my model, also, if it's possible to only change the thermostat and not the entire hose? I found this thermostat: 1K0 121 113A but I don't know if it's the right one. Sorry if I didn't explain it in the best way, english is not my first language, I just hope that people who had this problem on my model could help me!

37722
philipharmes
20-01-2021, 11:52 AM
Yes, 1K0 121 113A is the correct part.
Available through Amazon or eBay & many parts distributors.

It's easy enough to change yourself.
You won't loose much coolant, but need to have a bottle to top up the reservoir afterwards.
Robert06
20-01-2021, 02:46 PM
Yes, 1K0 121 113A is the correct part.
Available through Amazon or eBay & many parts distributors.

It's easy enough to change yourself.
You won't loose much coolant, but need to have a bottle to top up the reservoir afterwards.


Hello! Thank you for the reply!

Is this the right one?: https://www.autopieseonline24.ro/mahle-original/7815022 (https://www.autopieseonline24.ro/ridex/13641971)

If yes, I will order it right away!
philipharmes
20-01-2021, 03:56 PM
Yes, correct one.

Make sure you fit the same way as the one removed.
Robert06
20-01-2021, 05:34 PM
Yes, correct one.

Make sure you fit the same way as the one removed.

Sorry for the late reply! I have ordered it, do you have any tutorial you could link me to?
philipharmes
21-01-2021, 12:04 PM
Here is one from youtube, but in German I think.
VW Passat - Motor wird nicht richtig warm 7B 3C Thermostat DSG defekt 2.0l TDI - YouTube (https://www.youtube.com/watch?v=YVYvlQHts9I)

Pictures speak a thousand words as they say.

Don't know if it is the same engine layout as yours, but should be roughly in the same area.
Robert06
21-01-2021, 09:07 PM
Here is one from youtube, but in German I think.
VW Passat - Motor wird nicht richtig warm 7B 3C Thermostat DSG defekt 2.0l TDI - YouTube (https://www.youtube.com/watch?v=YVYvlQHts9I)

Pictures speak a thousand words as they say.

Don't know if it is the same engine layout as yours, but should be roughly in the same area.

Okay, thank you!