A4 b8 2.0tdi 105kW problem with coolant temperature

[Audidua]

Last year my temp gauge started to go down when driving especially when it is cold weather so I replaced thermostat with OEM 03L 121 113 A. After replacement nothing much changed but I did not pay attention because heating was good and fuel consumption also. Two weeks a go I changed coolant temperature sensor with OEM part just because I got it for bargain 8€ or so but nothing changed with coolant temperature. Connected my vcds and found no errors on engine and HVAC module. Coolant temperature readings are the same as gauge is showing on instrument cluster. After all of that I purchased aftermarket thermostat brand Febi Bilstein with opening temperature on 83 degrees celsius but situation got worse. My car is not heating like it was before with OEM thermostat and the temperature goes to 70-80 degrees na and if I stop on traffic lights it immediately goes down. The same thing happens if I drive slowly. I tried to raise rpm on idle to 3500rpm and hold it like that for a few minutes and then temp gauge goes up and stops on 90 degrees but when I release gas pedal temp is falling down immediately. This is very strange and I just dont believe that both thermostats not working well and coolant temperature sensor also. If you have some ideas what to do or check next please tell me I'm without any. Thank you all.

This morning after I drove 33 kilometers going to work.

http://uploads.tapatalk-cdn.com/20161027/ebd9b86393afeaf4401e416881430c7a.jpg




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[Gunnark100]

This morning after I drove 33 kilometers going to work.Sent from my iPhone using TapatalkNot a fact in your case, but few people were lucky after replacing this 1K0121113A in A4 2.0TDI

[Audidua]

What is that? Thermostat? Mine is 03L 121 113 A and replaced twice till now


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[Gunnark100]

What is that? Thermostat? Mine is 03L 121 113 A and replaced twice till now Sent from my iPhone using TapatalkSome places call this termostat, some cooler regulator etc,,,,your car has so to say two thermostats, this one is located between hoses, not the same place as normal termostat 03L 121 113 A!Translate with browser(one click), as i said, few people changed this out and solved problem, but not for all:A4 B8 - �е греет�� двигатель 2.0tdi | Audi Клуб (http://www.audi-club.ru/index.php?threads/ne-greetsja-dvigatel-2-0tdi.466975/)

[Audidua]

I looked in ETKA and part number 1K0 121 113A is for coolant regulator (or thermostat) for A3,Q3 and TT, no A4 8k. Here is link Online VAG spare parts catalogue: Volkswagen, Audi, Skoda, Seat, part number '1k0121113A' - coolant regulator (http://www.realoem.me/search/tvn/1k0121113A) just click on tab EUROPE and you'll see which model and year have that part.

[Gunnark100]

I looked in ETKA and part number 1K0 121 113A is for coolant regulator (or thermostat) for A3,Q3 and TT, no A4 8k. Here is link Online VAG spare parts catalogue: Volkswagen, Audi, Skoda, Seat, part number '1k0121113A' - coolant regulator (http://www.realoem.me/search/tvn/1k0121113A) just click on tab EUROPE and you'll see which model and year have that part.I know its not listed as separate part for 8k(you did not read/translated the link), it does not mean its not part of the cooling system:)! You can pay 3-5 times more and take full set with hose etc! As i said in first post, its not 100% solution for everybody!

[Audidua]

I did translate it and I understand what you trying to say but it is very odd this part isnt in ETKA for A4 b8 2.0 TDI. I checked whole coolant instalation and theres no such part even without part number. Can you find it your self and show me the illustration? Thanks


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[Audidua]

I've found additional info about that thermostat one of those men said that the fault was in the thermostat which is in 03L121157B tube. I checked with ETKA and there it is a coolant hose. Now I have to check under the hood how it looks like and if I can take it off and see if thermostat is in there and change it.

[Gunnark100]

As i said its part of the hose on b8, thats why you cant see this on diagram:

Last revision for hose i guess is M and hose number 23!

lower small hose left side there you see regulator!

http://i.ebayimg.com/00/s/NTMzWDgwMA==/z/makAAOSwzJ5Xf8UX/$_1.JPG

[Audidua]

Yes, number 23 is on illustration, 03L 121 157 B is part number for my car engine code CAGA

http://i63.tinypic.com/14ngv9g.jpg

[Gunnark100]

Good, now you can change hole hose, or just part of the hose, if regulator will not fix the issue, next one is return valve, which is also part of the same hose and you cant see this either:).

Good luck!

[Audidua]

Thank you, I hope this will fix the issue.

[Gunnark100]

Lets hope so, as the last guy on this russian link posted, he replaced both at the same time, so for him, no idea which was faulty!

return valve separate number is:
1J0122351 (http://www.nanodatex.pl/parts/part/vag-1J0122351.html)(20 pound or something like that)

[Audidua]

If I get it right number 1. is Regulator and number 2. is Return Valve?

http://i64.tinypic.com/ibyycn.jpg

[Gunnark100]

Should be yes!

Rura wąż wody Audi A4 8K0 B8 03L121157B 1K0121113A VAG. Nanodatex (http://www.nanodatex.pl/rura-waz-wody-audi-a4-8k0-b8-03l121157b-o208145.html)

[Audidua]

Thank you, thank you, thank you...I would not fix this without your help.

http://uploads.tapatalk-cdn.com/20161106/5225e12ea11c9726fcf0ac50c9533dbe.jpg
http://uploads.tapatalk-cdn.com/20161106/6c26e44e0a9a63bf1289cc81d3b309ed.jpg

I've changed the thermostat only and all is fine now. Thermostat was payed about £15 and was without OEM part number and Audi logo because it is treated and sold like aftermarket part. If you want to purchase it in official service then the price is 3x higher.
http://uploads.tapatalk-cdn.com/20161106/5143af4bae13d414d2db65bedec7b7bb.jpg
http://uploads.tapatalk-cdn.com/20161106/7ac9033679016a91325ee1e91bb6000a.jpg


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[Audidua]

Here I am with some news about coolant temperature. After thermostat 1K0 121 113A changed all was fine but last few days I've noticed that the coolant temperature is dropping on cca 83 degrees celsius if I set the heating on HI or little bit less. If the heating is set to 25-26C then all is good no oscillations at all even on idle. Is it the return valve 1J0122351 the issue now?


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[Audidua]

Here I am with some news about coolant temperature. After thermostat 1K0 121 113A changed all was fine but last few days I've noticed that the coolant temperature is dropping on cca 83 degrees celsius if I set the heating on HI or little bit less. If the heating is set to 25-26C then all is good no oscillations at all even on idle. Is it the return valve 1J0122351 the issue now?


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[Gunnark100]

Here I am with some news about coolant temperature. After thermostat 1K0 121 113A changed all was fine but last few days I've noticed that the coolant temperature is dropping on cca 83 degrees celsius if I set the heating on HI or little bit less. If the heating is set to 25-26C then all is good no oscillations at all even on idle. Is it the return valve 1J0122351 the issue now?
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I never tested any of my car like this, could be normal, especially for tdi engine. I would keep things as they are! Keep 20-25 and dont boil the egs:)

[Rob69]

If the engine is not working hard but gauge is sitting at 90' and you set the cabin heater to HI, a small drop in dashboard temperature is normal, especially we are now in lower ambient temperatures, does this happen if you are driving steady at say 2500rpm and then set heater to Hi?

[Audidua]

Temperature drops only when heating is set to 26.5°C no matter how I drive. It happens when car is stationary on idle and when I drive. Also it takes more time (and distance about 15 kilometers this morning, outter temp was about 0°C) for temp gauge to get on 90°C but when heating isn't set to high coolant temp is cemented on 90. Major problem is solved by thermostat change and that was most important for me because heating is working well again. This is now a minor problem which not affects heating or other vital functions and maybe I should not touch anything. tHAT RETURN VALVE can wait to be changed if he is a problem at all.

[turbozob]

Temperature drop is normal on all diesel engines. Most of the time I turn on inner air circulation, engine warms up quicker and temperature does not drop too much.

[turbozob]

In my car, now when outside temp is -10°C and when AC heating is turned off, engine temp. comes to 90°C after 8km, if AC heating is at HIGH the engine temp. reaches max 70°C if RPM is below 2000, if on highway the 90°C reaches after 16km. Which part could be defective in these conditions?

[blade6591]

hi, do you have manual or automatic gearbox ? I have same problem with seat exeo tdi caha engine..

[turbozob]

Manual.

[niall campbell]

I don't see a problem with whats happening guys

using the recirculation button will just lead to steamy windows

[blade6591]

thank you, i try to find it :)

[borut032]

I have the same problem on audi a4 b8 2012 (facelift). I buy 3 years old car.
I change thermostats (both) and sensors (both).

on the odometer shows always the same temperature (on the 1 post.)
then I look odometers on the ebay and on the car (audi a4 2003) and a6 2009.
the position of the temperature (cold engine) start at 50 C.
but on my, is lower then 50. so I decide to repair the odometer and set temperature index finger to 50.

when I drive, the temperature on the odometer is now ok (90 C)
34398

[Gunnark100]

So under engine ecu with vcds, temp is also 90?

[turbozob]

So under engine ecu with vcds, temp is also 90?Right, ECU and gauge value must match.

[Audidua]

If your car is facelift model there shouldn't be more than one thermostat. Where is second thermostat placed and which part number it has? As far as I know only preFL cars have two thermostats and one is hidden in rubber hose which connect oil cooler and exhaust gas cooler part number 03L 121 157 B

[borut032]

Yes,
Temperature on vcds is 85 C, odometer show 90 C. when I test whole odometer, all index finger came to max (also temperature), before hi isn't.
and then he is in the middle, like others. I think that now is ok.

But I don't know, why the temperature index finger in not in the correct position (manufacturer failure?)
What was with him, when the car was new....

[borut032]

no, my car is facelift, motor code CJCA. it has two termostat. On the block of motor and hose ....

[doktorrrr]

I have the same problem with my Audi A4 Quattro 2013. 2.0 TDI 110 kW. My problem is started after the replacement timing belt and water pump. My car is facelift but still, have two thermostats. Both of them replaced. Now, I'm interested in return valve in the hose. Can anybody confirm what is a solution of the problem?

[borut032]

Hello,
Do you have return valve? My has only hose termostat (second termostat) without return valve... in what position is temperature index finger on the odometer when the ignition is off? It must be minimum at 50 0C

[doktorrrr]

No. I'm looking for this return valve today. My car doesn't have this return valve. Can Audidua confirm solution of the problem?

[Audidua]

I dont know where no-return valve is on FL cars. Im looking for it on my A5 2.0tdi, found second thermostat only by now.

[doktorrrr]

So, you didn't solve your problem? I think that return valve doesn't exist in facelift models. I can't see return valve in hoses in my car 2013. model. Only second thermostat.

[Audidua]

No, I didnt but I think it is normal behaviour when I on motorway temperature sits on 90 degrees and when I'm driving on local city streets and heating is set on 24°C there is a little oscilation on temp gauge where not sitting on 90. I'll leave it like that will not care anymore.

[doktorrrr]

I'm freezing with 24ºC. If I set my heating on 26 ºC I feel a little heat only after 5-6 km. Temp outside is 8 - 13 ºC these days. It would be interesting to test our thermostats. Does it really open at 87 ºC or less?

[Renars]

No, I didnt but I think it is normal behaviour when I on motorway temperature sits on 90 degrees and when I'm driving on local city streets and heating is set on 24°C there is a little oscilation on temp gauge where not sitting on 90. I'll leave it like that will not care anymore.

Yes, it is normal behavior, because you are drawing heat away from coolant with cabin heater and engine in low load cant produce much heat.
Temp gauge shows 90 from around 75 to 120 degrees C. Thats how its designed

[Renars]

I'm freezing with 24ºC. If I set my heating on 26 ºC I feel a little heat only after 5-6 km. Temp outside is 8 - 13 ºC these days. It would be interesting to test our thermostats. Does it really open at 87 ºC or less?
Your coolant temp gauge will show 90 long before thermostat will start to open at 80 plus degrees.
Also cabin should be blasted with hot air long before that.

[doktorrrr]

Just to refresh the topic. Does anybody solve the problem with drop temperature? I have no problems in the summertime with Audi A4 B8 2.0 TDI 2013. But, this weekend I was on the mountain and temperature outside was about 2 degrees. My temp gauge was on the 50-60 degrees next 30 km. I was no heating in the cabin. Only after I came to the city (+10 degrees), my temperature gauge reaches 90 degrees.
Just to let you know, my both thermostats are replaced in the service dealership (two times). I also have Passat 2012 with the same 2.0 TDI machine. Passat doesn't have the problems at all in the winter time. Temp gauge is stack on 90 degrees and the heating in the cabin is excellent. So, I think that this is not normal behavior.

[Renars]

To make it clear !!!
Temp gauge DOESN'T show real temperature.
It shows 90 degrees from around 70ish to over 100. Its designed that way so you don't go to dealer asking why temp is moving around all then time,
but as we can see that haven't worked:D
In city driving if outside air temperature is close to 0 degrees modern diesel can not reach coolant temperatures of 90 or even 60 degrees even with thermostat closed and coolant not going to radiator, because your cabin heater is pulling all the heat out of it.
It will warm up only if its under load for quite a while - highway drive.
That's why its way more economical than petrol nonsense.

[doktorrrr]

I have a laser gun for temperature in hoses. The difference between the gauge and hoses is about 10 degrees. I'm aware that t
emp gauge DOESN'T show real temperature. However, difference can't be more than 10 degrees. What if your car is overheating and temp gauge is lie for more than 10 degrees and show you that everything is normal?
So, t
emp gauge DOESN'T show real temperature, but not too much. We talking about coolant temperature drop for more than 30 or 40 degrees than normal 90 degrees in downhill drive or idle. Sometime, I wait for green light on the semaphore and I see how the temp gauge drop for 10 or 20 degrees.
Also, in the summertime temp gauge is fine in the driving. It's stuck on the 90 degrees. But, I have noticed something strange. After long drive (outside temperature is about 30 degrees), and parking the car for 5 minute pause, when I'm starting machine again, temp gauge is on the 50 degrees. How can be possible that coolant temperature is drop from 90 to 50 degrees for only five minutes pause on the 30 degrees outside in July? Something in the cooling system doesn't work correctly, but car diagnostic doesn't show what is it.

[Renars]

You could use VCDS to see real coolant temperatures in at least 6 different places for your car.
Difference is way more then 10 degrees.
House after radiator could be minus degrees while engine gauge at 90 already since thermostat starts to open at 83 degrees.
Gauge will go to red section when coolant will reach dangerous temp, that's how its programmed !
Maybe next time check while driving with VCDS or any reasonable diagnostic tool, it will show you real situation.
While heating up your cars coolant even not pumped around and stays still to warm up quicker.
Before your laser gun experiment, please, do more reading on modern cooling system technology, its gone way different since 1980 now !

[Renars]

You are talking about coolant system as one loop, but its at least 4 different loops.
Lets say you started car dead cold in morning and its 0 degrees, then you are driving on country road for 5 minutes temp gauge is at 90 BUT thermostat is yet to open because its really never been over 80 degrees, its looping through engine and heater matrix only and that's like 1,5 liter of coolant. As you stop and idle your heater is pulling massive amount of available heat out of this 1.5 liters of coolant and of course it cools it down very rapidly !

[Novica]

I have same issue with my A6 2.0 TDI, 2011 C6 model (2008-2011), engine CAGB. I have changed main thermostat and hose thermostat, no change. I didn't change non return valve. No change, during outside temperature more then 10 degrees everything is normal, when outside temperature goes below 10Deg C, engine tempereture is depending on engine load.

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[Glen Norman]

Should be yes!

Rura wąż wody Audi A4 8K0 B8 03L121157B 1K0121113A VAG. Nanodatex (http://www.nanodatex.pl/rura-waz-wody-audi-a4-8k0-b8-03l121157b-o208145.html)

It might be a bit late but a very good flow digaram.
Diagram of coolant hose connections (https://workshop-manuals.com/audi/a4_mk3/power_unit/4-cylinder_tdi_engine_(2.0_ltr._4-valve_common_rail)_mechanics/engine_cooling/parts_of_cooling_system_(on_engine)/diagram_of_coolant_hose_connections/)

[Mio&drag]

Same problem here. Replaced regular thermostat Vernet 82°C also replaced Behr th5 75, but still dropping temperature if I drive out town, on lower RPM. Same Audi Caga 2.0 tdi a4 b8 105kw engine.
Next should be the valve? Does all 105kw has this valve?
(Picture with diagram is no longer available...)


Recent update:
Problem solved by replacing the valve
1J0122351 in hose.
I had two termostats Behr th 5 75 both in hoses. Probably previous owners service guy mixed them up.
Changed the upper part in hose (upper is the valve, lower is the inline thermostat). Tried the car for 20km, with heat on the max, and everything works fine! Glad if this helps anyone.