Audi B7 A4 2.0T Thermostat Replacement (DIY)

[dcain1993]

Hi, I wanted to contribute to this forum and to all Audi enthusiasts. I have used a countless number of guides on here and I really appreciate them. I already replaced my thermostat previously but it started leaking coolant and I got fed up with buying coolant constantly. So, I had another spare thermostat from my timing belt kit and decided on using it. I also purchased an O-ring seal that I did not previously, which I hope is the culprit to my leaking issue down there. So far so good though!

Also, the exact Audi I replaced this thermostat on is my 2006 Audi A4 B7 2.0T Quattro

Audi B7 A4 2.0T Thermostat Replacement

Tools Needed:
Socket Wrench
10mm Socket
17mm Wrench or 11/16 will fit (A good length as well)
Adjustable Pliers preferred or Channel Locks
30 Torx Bit Socket
6mm Hex Bit Socket
Flat Head Screw Driver
13mm Socket
Hose pick (Optional)
5mm Hex Bit Socket
Connector Tool (Optional)

Supplies Needed:

Thermostat (OEM: 06D121111G) (MPN: 06D121111G)
http://www.europaparts.com/thermosta...g-genuine.html
G12 Coolant (1.5 Gallons at least)
Distilled Water
O-Ring for center hose on thermostat (20x3MM) OEM: N90365302 MPN: N90365302
https://www.europaparts.com/o-ring-n90365302.html (This comes in certain kits as well)
Shop Towels
Brake Cleaner (Any cleaner really that you’re fond of)
Funnel
Rubber Disposable Gloves
A Container to catch coolant
Bungee Cord (Optional)




Here are a couple pictures of the leaking coolant



Step 1: Take off negative terminal on battery, I bungee corded it up. (10mm Socket) and Remove Engine Cover


Step 2: Remove serpentine belt partially off of the alternator by using the metal tab on the tensioner itself to allow slack. (17mm Wrench or 11/16)
(I secured the belt with a bungee cord as well, so that it would not fall accidentally)



Step 3: Remove upper radiator hose. (This hose does get adhered somewhat, be careful removing it.
I used adjustable pliers to move clamp and a flat head or pick to move gently around the hose.




Step 4: Remove larger hose (Flat Head Screw Driver)



Step 5: Remove the Alternators 4 Hex Bolts (6mm)



Step 6: Remove the 2 connections on the back of the alternator (One is a 13m Socket with a cap and the other is a connector plug) I used my connector tool to remove it but a flat head works as well.




Step 7: Remove upper thermostat hose with pliers on clamp. (Then wiggle loose)A flat head helps or I found that my pulley tensioner pin helped me)



Step 8: Remove Torx 30 screw on metal hose up top (Silver in color)



Step 9: Remove Torx 30 screw, center hose is metal (Black in color)


Step 10: Remove two hidden 6mm hex bolts above oil cooler, can be seen in picture or with an inspection mirror. (This holds the center hose in place)


Step 11: Remove center hose and push to side


Step 12: Replace the O-Ring on the center thermostat hose, mine tore from what I could tell from last time = ( (20x3mm)

Step 13: Remove bottom thermostat hose, pull metal clip with needle nose pliers (Be gentle with it as well)


Step 14: Remove 2 (5mm) hex bolts that attach thermostat to the engine block (Remove thermostat)


Step 15: (Optional) Clean area while everything is out


Step 16: Do the previous steps in reverse

Step 17: Fill expansion tank with coolant and let car run. (I drove mine about less than one mile and the thermostat opens up) I then proceeded to add more coolant. Also check and make sure that your gauge eventually goes to the 12 O’ Clock position




I hope you enjoyed my guide!

[new_era_inc]

Hi, I wanted to contribute to this forum and to all Audi enthusiasts. I have used a countless number of guides on here and I really appreciate them. I already replaced my thermostat previously but it started leaking coolant and I got fed up with buying coolant constantly. So, I had another spare thermostat from my timing belt kit and decided on using it. I also purchased an O-ring seal that I did not previously, which I hope is the culprit to my leaking issue down there. So far so good though!

Also, the exact Audi I replaced this thermostat on is my 2006 Audi A4 B7 2.0T Quattro

Perfect. Just one question, you mentioned about using 17mm for the serpentine belt tensioner. Did you remove bolts completely or just used a wrench to loosen the tensioner and slip the belt off ?

When I did my belts I just grabbed the tensioner with a wrench and loosened the tension to slip the belt off.


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[dcain1993]

Perfect. Just one question, you mentioned about using 17mm for the serpentine belt tensioner. Did you remove bolts completely or just used a wrench to loosen the tensioner and slip the belt off ?

When I did my belts I just grabbed the tensioner with a wrench and loosened the tension to slip the belt off.


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I used a 17mm wrench on the metal tab that measured about that size. From there I did move the tensioner and then slipped the belt off. Sorry if it wasn't clear, hopefully that hasn't messed anyone up.


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[new_era_inc]

I used a 17mm wrench on the metal tab that measured about that size. From there I did move the tensioner and then slipped the belt off. Sorry if it wasn't clear, hopefully that hasn't messed anyone up.


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That's what I thought. Thanks for clarifying


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[hemantpd1]

Hi All,

I have 2007 Audi A4 2.0T. My car's check engine light is coming on with P2181, which goes off after some time automatically. My car's coolant temperature never reaches to the midline in the gauge while driving, but the heater works fine. If I keep the car idle for some time, coolant temperature reaches to the midline. Once I start driving it falls below the midline. Please suggest what is the issue: CTS or T-STAT?

[dcain1993]

I would check the temp sensor and or thermostat. If you're going in there already though I'd replace it anyway just for peace of mind. It's a pretty quick process. Hopefully you got it figured out!


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[gym321]

I used a 17mm wrench on the metal tab that measured about that size. From there I did move the tensioner and then slipped the belt off. Sorry if it wasn't clear, hopefully that hasn't messed anyone up.


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Thank you, I saved myself $1050. Audi quoted me $1100 to replace it. It was easy, but I did have a tough time at first trying to get the belt back on. I originally removed the top 2 bolts on the tensioner to loosen the belt. I cound't get the bolts back in until I went back and read the above quote. 10 minutes wasted. I can be slow at times.

[mtroxel]

Thanks for the DIY. Suddenly my temp gauge never points straight up at 12:00, and it's 40˚F outside. I think this is my future.

[hemantpd1]

Just replaced my thermostat and everything is good now. I would really suggest everyone who are going to do this job to buy a cable hose clamp removal tool. It makes the life easy.

[rennwerkes]

Just replaced my thermostat and everything is good now. I would really suggest everyone who are going to do this job to buy a cable hose clamp removal tool. It makes the life easy.

+1 on this suggestion.
I just completed this job a little while ago and the hose clamp removal tool is a small cost to bear rather than trying to use pliers.
Makes clamp removal so much easier.
Then again, I ask myself what's wrong with the "regular" hose clamps???

[Dondbg]

Hey Guys. I'm about to replace mine, vag com shows fault which suggest a bad thermostat and temp doesn't reach the optimum 85'ish ( 22 O clock)
Which coolant to use , I guess I have G12 judging by the colour, is it ok to use G13 ?

Edit: actually how much coolant I will need , will the car throw away 1.5 Gallon ?

[SimbadCA]

2007 B7 A4 2.0T Quattro; Last weekend I replaced my t-stat assy. I have a small leak, perhaps from the center port. What's that port go to, and perhaps its the o-ring....anyone have a part number? The id on the t-stat is 25mm.


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[SimbadCA]

Logic is telling me that the previously mentioned 20x3mm o-ring is correct; id=20mm...od=26mm. OEM: N90365302

[SimbadCA]

I still need a little confirmation on that o-ring. ECS tuning indicates that the o-ring fits the B6 series and multiple VWs...but surprisingly does not list my B7.

[mtroxel]

Wouldn't it be easier to just go to the dealer?

[SimbadCA]

As it happens, they were open today on my way into another event. I have my o-ring.
From ECS, I had other items to purchase also...now waiting until next month.


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[AudiKilla]

Just replaced my thermostat and everything is good now. I would really suggest everyone who are going to do this job to buy a cable hose clamp removal tool. It makes the life easy.

Is this the tool you guys are referring to remove the clamps?
https://www.ecstuning.com/b-schwaben...170sch01a~sch/

[rennwerkes]

Is this the tool you guys are referring to remove the clamps?
https://www.ecstuning.com/b-schwaben...170sch01a~sch/

That's the one.
But I'd suggest checking on Amazon.
There are cheaper alternatives.

[SimbadCA]

I have one and use it often for each project. Still some clamps with insufficient room like connection to HPFP.
Worked great on the thermostat project. The hook and pick set are really nice too. ES#2778980


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[pimpbot]

My coolant gauge always reads 12 o'clock when cruising down the road. Sometimes during a long downhill (like a 500-1000' elevation change) the needle will migrate down to the 1/3 mark. Now, I use the Android app, Torque, along with a bluetooth OBD2 reader. The coolant reading in Torque is usually around the 85 degree C mark when freeway cruising, but goes up to 104C in stop and go traffic. During those long descents, it goes as low as 75C.

I know the coolant gauge on the dash is pretty much fiction. It may as well be a warning light.... cold, normal, and overheat.

A 20 degree C coolant swing (after warm up) in the normal run of things is really wide. I'm guessing the thermostat is stuck open a bit.

Does anybody else using Torque (or any other ECU - OBD2 reader software) see temp swings this wide?

Seems like my B6 1.8t A4 ran pretty steady around the 95-100C mark, but I don't know how calibrated that coolant temp sensor is.

[mtroxel]

A 20 degree C coolant swing (after warm up) in the normal run of things is really wide. I'm guessing the thermostat is stuck open a bit.

Does anybody else using Torque (or any other ECU - OBD2 reader software) see temp swings this wide?

I have VFIZ and my Ctemp is always on the DIS. Once warmed up, mine is always in the 93-96° C range. I never see 75° C, and where I live ambient temps were well below 0° C just a few months ago.

[pimpbot]

I have VFIZ and my Ctemp is always on the DIS. Once warmed up, mine is always in the 93-96° C range. I never see 75° C, and where I live ambient temps were well below 0° C just a few months ago.

Yeah, everything is pointing to the fact that my thermostat is stuck open. I guess that's better than stuck the other way.

I ordered parts, gonna get another jug of coolant from the VW Dealer ($25 vs $35 from Audi) and get messy.

Thanks for the input.

Any tips on refilling the coolant? Is there an easy way to 'prime' the other side of the t-stat? I always had trouble getting that to work. Maybe open a radiator hose and pour some coolant mix in directly?

[mtroxel]

Any tips on refilling the coolant? Is there an easy way to 'prime' the other side of the t-stat? I always had trouble getting that to work. Maybe open a radiator hose and pour some coolant mix in directly?

I've only drained the coolant out of this 2.0 about 3 times, but I've not had a big air bubble problem. I fill till it bleeds out of that bleeder screw on top of the black coolant tube. Then after I get it hot, I bleed steam off of that point, and at the bleeder point on the heater core hose. I've not seen this motor be that fussy with air bubbles in the 3 times I've had to refill.

[Azwan]

FWIW, I changed out the thermostat on my B7 Cabrio 2.0 using the guide presented early in the thread. Confirming that the longest time spent was wrestling to remove the lower connector, the biggest diameter of the three. The thing would not slide out easy at all. In the end I took off the old thermostat and then wrestled with that darn stubborn connector.

Once that is off everything else went quick, yep putting all back together took less time than taking everything off. Total time spent - 5hrs. Now the temp gauge gets to noon position faster than it has been in a long time since I owned the car.

[benditocarlito]

Thank you very much! This guide was great, surprisingly I did not struggle taking anything off since I had the right tools. My biggest pain was putting the belt and tensioner back on. All done in 3 hours

My thermostat wasn't bad but it was leaking, replaced O-ring in the middle pipe and installed a brand new thermostat with new seal since Audi didn't have just the seal and I couldn't have my car down for three days while they order it since it's my daily.

If anyone needs a thermostat I got one. Used but works great. Also comes with brand new seal and middle pipe O-ring


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[kbqueens7]

Great write up. I'll agree with an earlier poster that getting a clamp removal tool makes this job much much easier. I had to replace most of the coolant system this past week because the previous owner thought it was a good idea to mix in some prestone with the G12. Hence lots of corrosion in the pipes and I had to do a full flush and replacement of parts.

[slytwyn]

Following.


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[medrads2020]

Changed my thermostat today after throwing the P2181 CEL. I used this walkthrough step by step and got it replaced within no time! My coolant temp gauge now reaches the middle and stays there. CEL no longer lights up. Thanks for the excellent contribution, dcain1993!

Just a quick note - the ECS tuning thermostat and coolant kit does not provide the o-ring for step 12, so make sure you order one separately if you plan to use this kit!

[OlegB7]

I'm having an issue with car turning on and the fans turn on with it, I put heat to like 80 and max and it blows out cold and also the coolant level was -40° when I checked it with OBD11 I assumed it was the Coolant Temp Sensor so I replaced that and got a CEL for it I cleared it and still came back, the fans are still running every time I start up car and they don't turn off I'm not sure what it could be at this point the I'm going to replace the thermostat, begging of next week when it comes in hopefully see if that may solve my issue but if anyone knows what is causing this issue please let me know would really appreciate it.

[pimpbot]

I'm having an issue with car turning on and the fans turn on with it, I put heat to like 80 and max and it blows out cold and also the coolant level was -40° when I checked it with OBD11 I assumed it was the Coolant Temp Sensor so I replaced that and got a CEL for it I cleared it and still came back, the fans are still running every time I start up car and they don't turn off I'm not sure what it could be at this point the I'm going to replace the thermostat, begging of next week when it comes in hopefully see if that may solve my issue but if anyone knows what is causing this issue please let me know would really appreciate it.

I remember some of the older Audis and VWs had separate radiator fan switches mounted directly to the radiator back in the olden days of yore. That was a separate sensor than the coolant temp sensor on the back of the engine (I'm thinking B5s now... I don't know where the B7 sensor is) that drives the ECU and the needle in the cluster. It's possible your fan switch is bad. I think it warrants buying a Bentley manual to track it all down. I'll take a look at mine when I get a chance. I'm kinda curious myself.

Of course, first place to check is the engine ground cables and such. A bad grounding cable is often the source of many electrical gremlins.

[slytwyn]

Following


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[lumberwood]

Thanks for the great write up and solid pics, OP. Used this diy today and all went well.

Coolant hoses were all happily welded in place, so much time spent gently opening them up with the right pick tool and voila the all came off in one-piece, no damage. Patience pays off.

I lost about 1.25 - 1.5 gallons of mix, fyi. Chugga-lug. Everything back together, opened the breather hole on that top-most hard pipe atop the motor and seem to have gotten all the air out once the T-stat opened and things got flowing. Tested that theory with some hard pulls (brake bedding) after doing the front brakes, and all good no level drop in the expansion tank when I got home.

Cheers!

[HerNameIsBeast]

Has anyone attempted to do this without removing the alternator? I can't get that thing off as one of the bolts is stripped. Thanks.