# Temperature Gauge Stopped Working, WTF!



## i_baked_cookies (Aug 28, 2007)

Okay, so last night everything was working a-okay. I get in my car this morning, bright and early, and drive rush-hour traffic, 20 minutes, and notice that my temperature gauge won't move off of "C!" I even stopped for gas, restarted my car, and noticed that it moved a bit off of the lowest position, but just a hair directly onto "C." I know for sure the engine isn't cold... 20 minutes of driving. Blah. What could be up?


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## SilverSquirrel (Jul 24, 2006)

*Re: Temperature Gauge Stopped Working, WTF! (i_baked_cookies)*

http://forums.fourtitude.com/zerothread?id=4644183
me too....


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## i_baked_cookies (Aug 28, 2007)

Huh. It works now! Maybe it was just a freak thing. Bluh.


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## abadidol (Mar 1, 2009)

*FV-QR*

Mine goes works occasionally as well. Your check engine light may come on if the temp sensor stops working while the car is running.


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## crew219 (Oct 18, 2000)

Bad coolant temp sensor. It is located on the driver's side of the engine block. Should be a green or black sensor. Easy to fix.
Dave


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## SilverSquirrel (Jul 24, 2006)

*Re: (crew219)*

http://forums.fourtitude.com/zerothread?id=4644183
its grey. part #s and link to ecs in thread above.


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## abadidol (Mar 1, 2009)

*FV-QR*

It's too bad you can't merge threads...


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## i_baked_cookies (Aug 28, 2007)

Okay so I had my car in the dealer to have this fixed. Got it back, worked for one day... and then the next day the same thing happened: check engine light and the temp gauge on cold.
So I took it back, and they called today saying that they installed another new sensor, and it's doing the same thing (working for a little bit, then reoccurring), and that they would be "looking at the wiring," whatever that means. Needless to say, it's a bit frustrating, considering I need my car back tomorrow for a weekend trip! Plus I'm driving around this Chevy Cobalt, and it's making me want to puke on a kitten.
Any thoughts?


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## tp. (Nov 12, 2009)

S40 comment here


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## i_baked_cookies (Aug 28, 2007)

*Re: (tp.)*


_Quote, originally posted by *tp.* »_S40 comment here

I felt it coming. BTW, I used to have a 2002 S40. Whatev


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## dkenn75 (May 22, 2008)

I was driving the other day and randomly my temp gague went from Fahrenheit to Celsius for like a half a second out of nowhere.
How this helps you, idk. Keep us posted http://****************.com/smile/emthup.gif


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## Tcardio (Mar 19, 2009)

*Re: (i_baked_cookies)*


_Quote, originally posted by *i_baked_cookies* »_
Plus I'm driving around this Chevy Cobalt, and it's making me want to puke on a kitten.
Any thoughts?

Come on! You know the rules! IF your driving another POS, you need to post it so we can laugh. I mean, I had to drive this POS last week


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## warren_s (Apr 26, 2009)

Dood that S40 is so much better than your station wagon!!


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## i_baked_cookies (Aug 28, 2007)

This place has changed man, really changed


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## dmorrow (Jun 9, 2000)

*Re: (i_baked_cookies)*


_Quote, originally posted by *i_baked_cookies* »_This place has changed man, really changed









I agree, nothing relevent to say but doesn't stop them from posting.
The shop is probably right, if the sensor isn't the problem then it has to be either the wiring or the gauge itself.


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## SilverSquirrel (Jul 24, 2006)

*Re: (dmorrow)*

My gauge went dead again as well. and threw the CEL.
I changed the sender myself twice, and since 3 bad senders in a row isnt likely, I took it to my mechanic for some vag com lovin and wire chasing. 
He found an intermittent connection at the harness connector to the instrument panel.








All fixed for now. And got my blizzaks mounted up too! let it snow!


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## i_baked_cookies (Aug 28, 2007)

Just got a call from the dealer... apparently there are two sensors (one on the block and another one somewhere else?)... well apparently both were bad, and that's what caused the problems. So hopefully when I pick it up (and get rid of this turd Chevy), everything will work beautifully again. I was getting a little frustrated with the service, but they fixed this one for free (after I paid them to replace one sensor already). So, all in all, not too bad. Still kind of mad that they gave me a damn Cobalt... I've never NOT wanted to drive so bad in my entire life.


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## SilverSquirrel (Jul 24, 2006)

*Re: (i_baked_cookies)*

The second one is in the bottom of the radiator, drivers side. Same part #, but uses a metal clip, not plastic. I did mine as well, for the hell of it.
(3.2L)
Much easier to get to than the one in the head, but you will loose all your coolant, so buy some new G12. (dealer will most likely catch the old g12 in a bucket and re-use it. Hope that does the trick.


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## i_baked_cookies (Aug 28, 2007)

*Re: (SilverSquirrel)*


_Quote, originally posted by *SilverSquirrel* »_The second one is in the bottom of the radiator, drivers side. Same part #, but uses a metal clip, not plastic. I did mine as well, for the hell of it.
(3.2L)
Much easier to get to than the one in the head, but you will loose all your coolant, so buy some new G12. (dealer will most likely catch the old g12 in a bucket and re-use it. Hope that does the trick.

Indeed, yea, I'm glad they figured it out, because they called me yesterday and sounded like the didn't know exactly how they were going to figure it out, haha. I was imagining one of those "keep my car for 2 weeks to try and fix it" situations. See, now if they had any A4 loaners left, I don't think I would mind too much. But words cannot describe the Cobalt.


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## tp. (Nov 12, 2009)

so its ok now? why didnt u ask for a S40 loaner car???


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## i_baked_cookies (Aug 28, 2007)

*Re: (tp.)*


_Quote, originally posted by *tp.* »_so its ok now? why didnt u ask for a S40 loaner car???

somebody came and bought them all


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## SilverSquirrel (Jul 24, 2006)

*Re: (i_baked_cookies)*

My gauge is dead again. worked for 2 days after my mechanic said it was instrument cluster harness.
I know it is a flaky electrical connection SOMEWHERE, but there are more computers, modules, and senders on this thing than the space shuttle. Now i need to go buy a vag com and laptop fix it myself.


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## i_baked_cookies (Aug 28, 2007)

*Re: (SilverSquirrel)*


_Quote, originally posted by *SilverSquirrel* »_My gauge is dead again. worked for 2 days after my mechanic said it was instrument cluster harness.
I know it is a flaky electrical connection SOMEWHERE, but there are more computers, modules, and senders on this thing than the space shuttle. Now i need to go buy a vag com and laptop fix it myself.










I'm glad we're having the same issue, because after the second time getting my car back from the dealer (yesterday), it breaks again. Jeeeesauce. They've replaced both sensors twice now... so it's back into the shop next week so they can find out what the hell is causing it. It's quite frustrating... but why every time they replace the thing does it break the very next day? If it was a bad connection, wouldn't it be broken regardless of the condition of the actual sensor?


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## SilverSquirrel (Jul 24, 2006)

*Re: (i_baked_cookies)*

From what i can gather from the vag-com printout, an intermittent "implausable signal" from the temp sender g62 in the thermostat housing triggers a fault. The computer reads water temp as -40 deg C, which is an open circuit, or short to B+ , according to my bentley dvd.
this could be a loose connection for a fraction of a second, anywhere in the harness between the sender and the ecu. a simple ground wire, or loose connector, or a break in the wire somewhere buried deep,.
Once the software reads this fault, it deems all data from the sender to be less than trustworthy, and disables the gauge in the cluster, for spite, and the engine management runs on a default map for temperature based on what i dont know. after some period of time, or miles, or trips, the computer finally gets pissed off and lights up the check engine light. This has happened to me twice, despite replacing the senders each time, and replacing the g83 sender (in the radiator) for extra measure. 
the sequence goes like this:
temp gauge stops working one day for no reason. 
after a few days, check engine light comes on. 
after a few more days, take car to mechanic w/vag com, "implausable signal g62 -40 deg C etc.. reset fault.
now gauge works.
two days later, cycle repeats. 
mechanic checks wiring, finds "bad connection" at instrument cluster (which makes no sense according to wiring diagram). clears fault. gauge works.
cycle repeats again. going back to mechanic w/vag com next week to keep digging. Its getting to be an expensive little electrical gremlin. I was hoping audi fixed its electrical gremlin problems since my last audi, but i guess not.


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## SilverSquirrel (Jul 24, 2006)

*Re: (SilverSquirrel)*

OK. The cycle repeats.
This morning, with my temp gauge still not working, I went to my mechanic.
Vag Com shows fault P2181 coolant performance, implausible signal.
No G62 ECT sensor faults recorded. I had to get to work, so we left it at that. Some research here and in my Bentley suggests P2181 could possibly be thermostat on the way out. (plenty of heat within 5 or 6 minuts on a 20F day would suggest intermittent or partial stuck open).
On my way home tonight, i had my mechanic vag com again, but this time clear the fault (we didnt do that this morning, i realized). Here is what happened.
Engine running, vag com connected. Temp gauge dead (car warm).
Clear fault code P2181.
Temp gauge instantly rises up to 11'oclock. (should be at 12:00 noon at operating temp)








To me, this proves my theory that the engine management software is written to disable the temp gauge if there is unreliable temp data or possible performance issues with the cooling system. 

My mechanic has worked on VAG cars for some time, and is one of the most knowledgable independant VAG techs I have met in this neck of the woods, and he was skeptical of my theory, but now agrees, having worked on hundreds of late model Audis and VW, this is the first time he has seen this happen, BUT IT DID HAPPEN! 
Now i need to fix my cooling system. Next free weekend, I will change the thermostat. Damn. what a pain.


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## sciblades (Oct 21, 2008)

mmm i might have the same problem, so i dont' just change out the coolent sensor?


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## sciblades (Oct 21, 2008)

also what is the milage on your guys cars?


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## SilverSquirrel (Jul 24, 2006)

*Re: (sciblades)*

vag com for fault codes first, before you "fix" anything.
my car has 57k mi.


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## sciblades (Oct 21, 2008)

i had it checked said the sensor is bad.
but driving around today my ac stopped working i assume this is because my cluster is not working and my fan is being used to cool the engine...


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## SilverSquirrel (Jul 24, 2006)

*Re: (sciblades)*


_Quote, originally posted by *sciblades* »_i had it checked said the sensor is bad.
but driving around today my ac stopped working i assume this is because my cluster is not working and my fan is being used to cool the engine...

no way to know.
btw, this thread is for 3.2 vr6 motor only. 2.0 turbo is different.


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## ECS Tuning - Audi (Oct 12, 2009)

silversquirrel, Email replied. I'll post a theory here as well:
If your thermostat is not functioning properly, perhaps your computer is expecting a plausible signal but is getting an implausible signal. That is to say you computer EXPECTS your thermostat to be opening properly but it isn't. So when your CTS's are getting signal, the computer is expecting different values and is negating them because the water isn't as cool as it is supposed to be? Granted it is just a theory, but it is the only way I can think to explain intermittent failure after a code reset. I agree with the threads, thermostat is next on the list. I would also do a full coolant flush as maybe the previous owner mixed coolants. This would be oxidizing your AL block improperly and potentially harming your sensors, thermostat and block.


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## Rogerthat (Oct 23, 2005)

*Re: Temperature Gauge Stopped Working, WTF! (i_baked_cookies)*

you should check out this thread. http://forums.vwvortex.com/zerothread?id=4725970
Oh wait.....what?


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## madcowz (Jan 9, 2002)

*Re: Temperature Gauge Stopped Working, WTF! (Rogerthat)*

Did this turn out to be a bad thermostat or a wiring short?


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## SilverSquirrel (Jul 24, 2006)

*Re: Temperature Gauge Stopped Working, WTF! (madcowz)*


_Quote, originally posted by *madcowz* »_Did this turn out to be a bad thermostat or a wiring short?

My car it was a bad thermostat. no problems since replacing it.
No idea what cookie bakers problem turned out to be, he didnt post up.
most likely tstat, 
























_Modified by SilverSquirrel at 6:16 PM 3-28-2010_


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## abadidol (Mar 1, 2009)

*FV-QR*

Odd... I think my cabin thermo is shot, (AC makes odd noise, doesn't seem temps work) But ever since I brought my car in for the recall and they updated my computer my coolant sensor works fine and has not set off any error messages since.


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## SilverSquirrel (Jul 24, 2006)

*Re: FV-QR (abadidol)*

wtf is a "cabin thermo"


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## abadidol (Mar 1, 2009)

*FV-QR*


_Quote, originally posted by *SilverSquirrel* »_wtf is a "cabin thermo"










I think its the thermostat sensor for the Cabin Temp....


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## xgarage (Oct 14, 2004)

I'm now having this issue. Do I need to replace just the thermostat? Any DIY available?


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## KnockKnock (Jun 30, 2005)

*me too*

Mine died last week too. From researching it looks like there are two temp sensors, and one thermostat w/housing. These days a thorough job will do them all (~$40 each for parts). Early on dealers were replacing one sensor, then customer came back with same issue, then they'd replace the 2nd sensor, then the third time it broke, they'd do the thermostat & housing. Lots of frustration and extra labor.

I've read here that some are happy doing just the thermostat, but it's still a PITA to get to.

I got a quote from a Dealer for $745. Found an independent shop to do it for $450. Hmmmm. I think I'll have them do my timing belt while they're at it and have the intake and alternator off.


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