Temperature gauge not working

DisturbedCat

Member
Joined
Mar 14, 2007
Location
Kansas City
TDI
One
I have an 02 TDI Jetta. The temperature gauge is not doing anything. Anyone run into this problem before? I am assuming some kind of temperature sensor has gone bad? Thanks.
 

tdiAlex

Veteran Member
Joined
Jun 4, 2008
Location
Toronto
TDI
01 Jetta
Slightly off topic.
Is it normal for the gauge to stay at 90 all the time when in actuality the temp reads 100 (via vag)

Thanks
 

TDIFanatic1.9

Veteran Member
Joined
Jan 9, 2007
Location
South Africa
TDI
1.9 Jetta TDI
Yes VW wrote the code controlling the gauge so that it sits still, not to bother the driver. I've heard stories that when it eventually goes over 90 and up its already too late and damage have already been done. There is some members that changed the rom code that the gauge reads more linear and move with the temp.
 

tttthumper

Veteran Member
Joined
Jan 9, 2008
Location
Pickering, Ontario
TDI
2006 Jetta TDI
I believe I'm having the same problem, and just wanted to confirm.

Little while ago (week or so ), I noticed my gauge was not going up to 90. So I switched over my Scangauge and monitored it. SG can show 82, 83,or 84, and my dash gauge was still at bottom left. So I understand it might not be "90", so it doesn't go 1/2 way.

Today I noticed that my Dash gauge went up to 90, even though SG was showing only 75. As my car warmed up to 85 or so, my dash gauge then fell back down.

I understand it might be the temperature sensor, but 2 questions.

What does SG get the # from?

Any harm being done, as the temperature still seems to be up to normal.
 

Rickstah

Veteran Member
Joined
Feb 5, 2002
Location
Yukon, Oklahoma
TDI
NB, 2002, green, Eurotek STG1
Just a suggestion...mine was going over the halfway mark occasionally, fluttering back and forth at odd moments. I was going to take it out and replace it when I realized I had the wrong replacement, so in essence I merely pulled it out a little, rotated it some while putting it back in, and added a little di-electric when I plugged the harness back in.

This did something, because my temp gauge went back to registering normal and sometimes just a hair below halfway, and it hasn't fluctuated in about a month or more. Not sure what this means, but it made my fluctuating stop for now. I did add a little new fluid back into the round container after some leaked out, but that was the extent of it.
 

HopefulFred

Veteran Member
Joined
Sep 5, 2002
Location
Atlanta, GA
TDI
Golf, 2006, Indigo Blue
I dont know where there may be redundant temp signals (I'm sure someone else knows). On the other hand, if you can't trust your gauges, what good are they? It shoud work properly.
 

Rickstah

Veteran Member
Joined
Feb 5, 2002
Location
Yukon, Oklahoma
TDI
NB, 2002, green, Eurotek STG1
bad news :)...you can't really trust your gauge in your dash, at least for mine...like feeling your dashboard to see if the engine is overheating...ok, kind of :)
 

n8ronJ

Veteran Member
Joined
Oct 11, 2007
Location
Niagara Frontier - Somerset, NY
TDI
2014 BMW 328d XDrive, 2003 Jetta GLS TDI 5speed Platinum Grey (sold), 2010 Jetta 6speed (bought back)
I hope this is on-topic enough. If it isn't please re-direct me. Lately, my temp gauge shows that I'm running cooler than I should. I'm assuming "should" is at the 190 in the center of the gauge - where it always has been. So, TDI is running a couple of marks below that. Fluctuating when the TDI is warming up but finding a consistant place to land once normal warm-up is achieved.
A couple questions:
Where is the temp gauge sensor? Is it in the reservior for the coolant?
It "looks" as though my coolant level is up to where it should be - if it were too low, would I have this fluctuating gauge issue?
If I'm running low on coolant - I've seen no puddles or drips or excessive steam so where's it going?
Is it time to flush the system anyways? I'm at 82k and climbing. Or can it wait 10k or so until I do the TB change?
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
The temp. gauge sensor is both part of the on board diagnostics system as well as the dash mounted gauge. It is located on the left rear of the engine. The newer ones are green in color, and by replacing the sensor should correct any and all gauge fluctuations. That is if your gauge suddenly drops, then the sensor is the most likely culprit as it was on my 05 Golf.
 

n8ronJ

Veteran Member
Joined
Oct 11, 2007
Location
Niagara Frontier - Somerset, NY
TDI
2014 BMW 328d XDrive, 2003 Jetta GLS TDI 5speed Platinum Grey (sold), 2010 Jetta 6speed (bought back)
I'll look for it in the left-rear. What is the sensor looking thing that is attached to the overflow canister?
The gauge was acting weird. My drive yesterday was 17 miles and within a 3-4 miles the car is usually warmed up. The temp outside was 80 degrees too. The darn thing was running 2 hash marks below the 190 line. I made my stop and shut the car off for 5 minutes. Started her back up and it's up to the proper temp reading. This morning the darn thing is running around 1 hash mark below the 190 line.

I guess having a bad sensor would make the most sense here. Is a stealership the only place I can get a sensor from?
 

biopete

Veteran Member
Joined
Apr 4, 2005
Location
Nashville, TN
TDI
A3 Jetta 1998, A4 Jetta 2001
The temp sensor has 4 wires -- 1 goes to the ECU, 1 goes to the temp gauge on the dash. I have problem of gauge not moving at all on a 98 Jetta even though car is warm. Need to check with vag com today. If vag com shows car is running between 80 and 90 C that is great.
 

n8ronJ

Veteran Member
Joined
Oct 11, 2007
Location
Niagara Frontier - Somerset, NY
TDI
2014 BMW 328d XDrive, 2003 Jetta GLS TDI 5speed Platinum Grey (sold), 2010 Jetta 6speed (bought back)
I'll start with the gauge first. Thanks for the input.
As a quick question though - What's the probe looking thing in the coolant overflow with the elec connection on it? I was thinking that it was for the temp reading.
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
I think it monitors the amount of coolant you have.
If the level of fluid falls below the probe, a warning light on the dash will glow.
 
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