# 225 is reading very hot but i dont think it actually is..



## aTTenzione (Aug 18, 2009)

so the past couple or few weeks while driving my temp gauge would read a notch below dead center. sometimes it creeps up to a notch hot but before long goes back to below dead center or center. tonight for the first time it went pretty much all the way hot and the coolant thing started beeping and flashing. i pulled over shut her off popped the hood and nothing out of the ordinary. fans where on but no smoke or leaks. and coolant was in the resovoir. drove some more after a few mins with it off and same thing. pulled over again waited then started back up. on the last attempt and thank god the ride to home base it stayed center/1 notch cool. is it something i should just stop driving over or just the coolant temp sensor like i assume?


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## Marcus_Aurelius (Mar 1, 2012)

First thing I'd suggest is to replace the CTS, the fact that the dummy gauge is going cold or hot points to the possibly of a failed CTS (they're cheap and easy to replace too). 

The second thing, if that fails to fix it, is a faulty gauge in the cluster. This can be diagnosed by checking the coolant temp reading in the climate control. Recirculation/up and turn the left dial to 49C will give you actual temp reading independently of what the gauge is reading. Good luck! :beer:


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## aTTenzione (Aug 18, 2009)

thanks. not sure if i understand that last part on how to get actual temp. so pretty much it can be a false alarm and the cars fine to drive right? cause on cold mornings like today when i start it up the coolant thing beeps and flashes like when it gets hot but im used to that one by now and i know it goes off after a few mins. i drove today and it was fine never went above dead center


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## Marcus_Aurelius (Mar 1, 2012)

Most likely the CTS, but like I said, if it's not it could be a failure in the cluster readings. If that's the case, then an easy way to test is to access the climatonic readings that read actual values from the temperature sensor (independently of what the cluster gauges are doing). 

This video will help you visualize what I was saying about accessing the true sensor readings with code 49c
https://m.youtube.com/watch?v=gU6aiySTHpU


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## aTTenzione (Aug 18, 2009)

ok thanks for the vid. went to advanced auto parts got the CTS for $9. replaced it in the parking lot and topped off whatever coolant leaked out. on the way home i was still reading as high as 110c- and as low as 78c. it seemed to stay on the cooler side the more i drove it tho and the gauge still dipped down 1 notch cool when driving home. what the FRIG


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## aTTenzione (Aug 18, 2009)

im doing second timing belt/waterpump/thermostat soon. maybe the thermostat is reading wrong? i have a half hour drive to work soon so we'll see what happens.


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## Marcus_Aurelius (Mar 1, 2012)

A thermostat will stick either part/full closed or opened, not swing back and forth widely. Check the true behavior in the climatronic.


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## aTTenzione (Aug 18, 2009)

update-- still not getting a solid 90ish reading on the climate control. i had it on 49c the whole way home last night and it was pretty much on 73*c the whole way home. it was late so i didnt get many traffic lights plus it was cool out and i had the heat on. i still dont think any of that would give me a 15degree difference and one notch below center on the cluster.when i got home and sat for a minute it would go up to about 80ish degrees and center out on the cluster. dont get me wrong id much rather have that reading instead of severe overheating but i guess i better look elsewhere for my problem besides the CTS.


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## Marcus_Aurelius (Mar 1, 2012)

With the CTS ruled out, and the climatronic test confirming the wild gauge readings, it's likely the thermostat. They're cheap too, but not as easy as the CTS to swap out. I guess you have one diva stat :screwy: ... sometimes sticking open and sometimes sticking closed, resulting in the cold operating temp one one day, and randomly overheating the next.


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## [email protected] (Dec 14, 2013)

Also if you bought the 9 dollar version you can cause yourself a lot of trouble get the green top OEM before you go tearing things apart. Just my 2 cents I had an off brand CTS cause me all kinds of hell


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## aTTenzione (Aug 18, 2009)

[email protected] said:


> Also if you bought the 9 dollar version you can cause yourself a lot of trouble get the green top OEM before you go tearing things apart. Just my 2 cents I had an off brand CTS cause me all kinds of hell


really? what kind of trouble? it was easy enough to install so i dont mind doing it again


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## [email protected] (Dec 14, 2013)

It was giving incorrect readings


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## crono35 (Apr 29, 2007)

Is the dash reading the same as the 49c reading? I believe they're fed off different sensors, but not 100% sure on that.


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## aTTenzione (Aug 18, 2009)

crono35 said:


> Is the dash reading the same as the 49c reading? I believe they're fed off different sensors, but not 100% sure on that.


yea they both seem to be right on the money with eachother. after driving it a few times with the new one in, it stays at around 80*c. sometimes dips down to mid 70s along with the needle going below halfway point. if i come to a stop for a minute or more it creeps up to as high as 99*c. then when i start driving almost automatically goes down again. this is all in very cool weather and with the heat constantly on. im not complaining honestly i think its doing fine. and just a side note -- this took me less than $20 to fix and about 10 mins of my time. woulda been less if i knew exactly how to get it out. when i was researching this problem i read on another forum that the dealership wanted to charge this kid $400 to do a CTS. you really gotta be kidding me with that price.


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## Marcus_Aurelius (Mar 1, 2012)

Honestly man, I wouldn't call victory yet. Operating temperature, when things are normal should NOT have these big swings. The thermostat should be regulating (under normal driving conditions) in a narrow temperature window. I'd say 88c-92c is a normal range with a 90*c thermostat. 

Going as high as 99*c shouldn't happen under normal driving conditions (especially in cool weather) -- and you should not be dipping as low as mid-70*c (a driving condition where the oil could be too cold to properly lubricate and burn contaminants). My advice is to not be satisfied with regular operating temperature having such a big delta.


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## [email protected] (Dec 14, 2013)

Honestly I agree with max I ended up changing NY thermostat as well before I ran proper temps and its cold where I live. Lucky for me it was under warranty.

First temp sensor was done.

No results.

So then thermostat.

Still not proper temp.

Then an OEM CTS.

Some improvement.

Confused mechanic
They checked all kind of things then finally broke down and replaced the thermostat again with a more expensive one.


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## [email protected] (Dec 14, 2013)

So my advise to anyone reading this is never try to save a little money on sensors and thermostats.

If I had to do the thermostat twice that would have been a huge pain.


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## aTTenzione (Aug 18, 2009)

WELP.. it happened again today.for the past couple days every time i drive ive had the climate control setting to 49c just to keep an eye on it. it seemed to be working fine. just running a little cooler than normal. then today out of nowhere i noticed the needle going past halfway a little, then alot, then saw the cc read 121*c!! then the beeping started and whatnot. then almost as soon as it started, it went back down to 78*c and the needle dropped and the flashing coolant warning went away. this happened on the way to and the way home from my parents house just now and they live about 10 mins away from me not even. one thing i noticed--- the other day when i was getting these severe overheating readings, it was raining. same thing with today. could something be getting wet and giving me this horrid reading?


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## [email protected] (Dec 14, 2013)

That wouldn't explain it running cool. Its your thermostat has to be it probably getting stuck open then stuck closed.


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## aTTenzione (Aug 18, 2009)

[email protected] said:


> That wouldn't explain it running cool. Its your thermostat has to be it probably getting stuck open then stuck closed.


im just curious if im doing any damage when it gets hot all the sudden or if its just a false alarm. it has to be considering in less than a minute it has a temp change of about 50 degrees celsius. i heard a sensor in the actual coolant reservoir could cause some controversy...


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## aTTenzione (Aug 18, 2009)

i just read that it could possibly have something to do with the power steering belt... i am getting noise when i turn left from the pump or belt. sounds more like the pump.. anyone have anything like this happen to them?


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## lite1979 (Sep 9, 2005)

Have you ever replaced the water pump? It's a PITA since it involves taking off the timing belt and the passenger's side motor mount, but a lot of OEM water pumps had plastic impellers that were fastened to the spindle with knurling. They have a tendency to crack, allowing slippage of the plastic impeller at certain rpms, but not all the time.


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## aTTenzione (Aug 18, 2009)

lite1979 said:


> Have you ever replaced the water pump? It's a PITA since it involves taking off the timing belt and the passenger's side motor mount, but a lot of OEM water pumps had plastic impellers that were fastened to the spindle with knurling. They have a tendency to crack, allowing slippage of the plastic impeller at certain rpms, but not all the time.


yes i did it with the timing belt with the metal impeller. HOWEVER at 189,000 miles im just about due for another tbelt waterpump job. im actually buying the kit tonight. i had suspicion that it could be the pump but that wouldnt explain why it only does that when its raining out.


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## Marcus_Aurelius (Mar 1, 2012)

aTTenzione said:


> i just read that it could possibly have something to do with the power steering belt... i am getting noise when i turn left from the pump or belt. sounds more like the pump.. anyone have anything like this happen to them?


Accesorry belt likely have nothing to do with your problem. If you were slipping on the water pump, you'd have overheating problems and none of the overcooled conditions.


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## Marcus_Aurelius (Mar 1, 2012)

aTTenzione said:


> yes i did it with the timing belt with the metal impeller. HOWEVER at 189,000 miles im just about due for another tbelt waterpump job. im actually buying the kit tonight. i had suspicion that it could be the pump but that wouldnt explain why it only does that when its raining out.


I think your problem isn't related to rain, and it's just coincidence that is was rainy when you had the problems occurring. My money is on a sticking thermostat (sometimes sticking open, sometimes sticking closed). Since you've already replaced the CTS and the problem persisted, and the climatronic is confirming/ruling out the cluster, the next logical target is the thermostat. :beer:

PS: there is no temperature sensor in the coolant expansion thank


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## aTTenzione (Aug 18, 2009)

alright well timing belt/water pump/ thermostat where ordered. im blessed being that my best friends sisters boyfriend is an audi tech and that whos getting my car soon as it arrives. i'll have all my answers soon hopefully


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## aTTenzione (Aug 18, 2009)

update -- the past couple days have been sunny dry and cool. ive had no overheating incidents. im almost 100% convinced it has to do with the rain or water in some way. i did a general google search of audi overheats in rain. the serpentine belt came up a few times but i just had mine done over the summer. either way ive been driving with 49c on every time now and my temp on that fluctuates from usually mid 70*celsius- 80*celsius. yes i know thats below normal. in traffic it will go up to 90 or a little above 90 but the needle stays centered never above, then goes back down to 1 notch below center when i start driving again and will bounce around from there to center every so often. moral of the story is ---- im pretty sure water is the culprit in one way or another.:thumbdown:


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## Marcus_Aurelius (Mar 1, 2012)

Don't worry, as long as you change the thermostat the rain will leave your car's operating temperatures alone! :laugh:


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## [email protected] (Dec 14, 2013)

You can lead a horse to water... But you can't make it change it's thermostat.


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## aTTenzione (Aug 18, 2009)

i really hope you guys are right but i still think its something slipping! it happened again tonight but no rain :sly: only for a second though. i was turning onto the highway and noticed the needle going just past center. the car wasnt even fully warmed up yet. i looked down at the climate control and it read 121*c but literally for like 6 seconds long then shot back down to 70 something. the needle didnt go all the way hot with coolant light beeping like in the rain but it did START to do it. thank god my timing belt kit will be here tomorrow


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## Marcus_Aurelius (Mar 1, 2012)

Nothing slipping can make your car run cold (a slipping belt over the water pump would only cause overheating). Only an open thermostat can cause over cooling AFAIK!


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## rodhot (Jan 4, 2012)

*same here*

my 2001 TT 225Q's temp gauge has been off since purchase 3 yrs ago. it used to start at 1/4 + go to 5/8, lately its almost half to start + hits 7/8, no overheating. from owning an 01 jetta 1.8T i popped in the green top sensor asap, my cluster is toast + since my baby sets in the garage in winter maybe this is to send for cluster-gauge repairs. i had fan issues + replaced the unit under the battery box last year


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## aTTenzione (Aug 18, 2009)

update for anyone that might encounter this in the future--- got the car back from timing belt water pump tstat etc service yesterday. no more cool readings but still getting the extreme overheating readings. my mechanic tells me its NOT overheating and that its probably the CTS wich if you remembered i replaced about a week ago with an aftermarket $9 one. he has an oem one for me we're gonna pop in later today and see if that fixes it. so yes im back to square one. we'll see if that fixes it.


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## aTTenzione (Aug 18, 2009)

ok so after doing timing belt thermostat waterpump service and a bunch of other stuff AND fixing my CTS problem, it started again today. a little over a week ago i put in the new OEM coolant temp sensor. i had ZERO "overheating" issues until today. same thing. the climate control 49c setting was reading 100-110 degrees celsius then would JUMP to 121, needle moving with it, then back down after a min or so. what the HOLY HELL is going on here.:banghead::banghead::banghead:


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## [email protected] (Dec 14, 2013)

Bad thermostat, air in the cooling system from not being properly bleed. Or o **** I have no idea.


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## [email protected] (Dec 14, 2013)

Just so you know I went threw similar problems but a shop had to do the work as it was under warranty and the thermostat had to replaced twice.


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## aTTenzione (Aug 18, 2009)

[email protected] said:


> Just so you know I went threw similar problems but a shop had to do the work as it was under warranty and the thermostat had to replaced twice.


i dunno the chances of that happening are slim i think. it has to be a wiring issue or something.


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## GLI_Jrock (Dec 29, 2007)

I have a very similar problem been to my mechanic a bunch of times, I changed my thermostat my CTS all cooling hoses to silicone and replaced all plastic parts like the T connections and coolant flange thermostat housing, also replaced the fan switch under battery with new, I still get really hot readings and my mechanic says its not overheating, my fans don't come on until temps read 120C I've seen it go as high as 125C but no warning lights in dash. He says its the gauge cluster, but I suspect it's more sinister because every once in a while I need to top up my coolant, as if I'm losing it from boil over or another place. Watching to see where this goes


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## Marcus_Aurelius (Mar 1, 2012)

If all these things are fully ruled out, locket air pockets, and bad reservoir caps would be next on the list.

When filling our cars after draining the coolant, proper burping procedure is needed. The reservoir need to be unbolted and raised up so the feed line is the highest point in the system ... then refill the coolant. The front end needs to be raised and the heat put on full blast to fully circulate fluid in the whole system and evacuate any air pockets. 

The cap is also a pressure bypass that regulates pressure in the system. When pressure exceeds what the caps allows, it vents the excess and regulates the system. A bad cap can allow pressure to rise and cause overheating. I'm on my third cap in my TT, so they do fail. 

And finally if all that fails, their is always the possibly of clogging in the radiator and leaky head gasket problems to investigate.


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## [email protected] (Dec 14, 2013)

Marcus_Aurelius said:


> If all these things are fully ruled out, locket air pockets, and bad reservoir caps would be next on the list.
> 
> When filling our cars after draining the coolant, proper burping procedure is needed. The reservoir need to be unbolted and raised up so the feed line is the highest point in the system ... then refill the coolant. The front end needs to be raised and the heat put on full blast to fully circulate fluid in the whole system and evacuate any air pockets.
> 
> ...


This. I vote air pockets.


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## aTTenzione (Aug 18, 2009)

[email protected] said:


> This. I vote air pockets.


i dunno this wouldnt explain why it happens mostly when raining out. my problem really seems more like an electrical issue. plus it was happening before the timing belt service and remains after. i had it done by a professional audi mechanic so im sure he took the steps to prevent air pockets. plus when i put the oem cts in i had no issue for a week until it happened again so i dont think it would take that long for it to happen if it where just air pockets. i posted about this on ttforum and am being told to check the connector to the cts and connections to the ecu.


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## GLI_Jrock (Dec 29, 2007)

Air in the system is a what I've been told b4, why is it so hard to bleed this system, how does the dealer do it? and, I will be buying a new cap


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## grahamdini (Apr 13, 2004)

I'd get your cluster checked.


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