Coolant Temp Sensor Replacement

verbalnoncents

Veteran Member
Joined
May 21, 2004
Location
Toronto, Canada
TDI
Sport Edition 2004
The little tab thing on the edge needs to be gently pushed away from the sensor. Then you grab the whole black part that the tab thing is attached to and pull the sensor end and this will allow you to separate the two.
 

TDIfor

Veteran Member
Joined
Aug 20, 2003
Location
Logan, Ohio
TDI
'02 NB Double Yellow
OK, now MY really, really detailed directions inquiry:

Where do you drain block coolant? If the radiator is not a good location, where else is there?

thx!
 

TheGreek

Well-known member
Joined
Jul 29, 2008
Location
philly
TDI
golf soon i hope!
be VERY careful pulling the c-clip tab off that holds it in...i tapped it with a screwdriver and hammer, and it broke off a chunk of the housing....it still held the sensor and i put some crazy zip ties on it too...hopefully that works...

also...the plug is next to impossible...i would recommend take the air hose off at the intake...one clamp...then the top of the airbox off on the other side...two phillips screws....next take out the bottom half of the airbox...two 10mm bolts...one close to the windshield and the other down in there by the battery...be careful with the second one not to drop it...once you have the entire air box out...you can probably use needle nose pliers or a screw driver to pry the c-clip tab off that holds the sensor in the housing...then...once the sensor is out of the housing, there is a clip that holds the wires onto the block...you can then pop that off and pull the entire sensor while still plugged in to your viewing...its much easier to get that wire off the sensor from this angle....
 

TheGreek

Well-known member
Joined
Jul 29, 2008
Location
philly
TDI
golf soon i hope!
as for the coolant...put a jack on the driver side rear corner...and a wedge in the passenger front tire....jack it up as high as you can....this will get the coolant away from the housing...i still lost about a pint or so, but there was still plenty in the reservoir...you could always add some water to it to get it back up but i didn't notice much of a drop
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Pulling the air hose and air box out is what saved me.
The old sensor and O-ring came out together, but the new one just did not want to go in due to the limited space with the air hose/box in the way. I could have saved most of my coolant if I had made a larger working area prior to removal of the sensor. Mine is an automatic, thus no coolant GP's.
 

Ricosuave

Veteran Member
Joined
Feb 10, 2002
Location
Calgary, Alberta, Canada
TDI
See signature!
paramedick said:
Well, I ain't that fast (old and slow) and invariably the O ring doesn't come out, so I use an alternate method.

I use an 18 inch piece of clear tubing of the appropriate size. Clean the drain nipple, attach tubing and route to empty gallon milk jug. Open the drain and fill the jug. Close drain, pull the tubing, and cap the jug.

Now change your temp sensor at your leisure. No spillage. Pour the coolant back in.
was just wondering where the drain nipple is located...
 

paramedick

TDIClub Enthusiast, Vendor
Joined
Jul 29, 2001
Location
Versailles, Kentucky
TDI
2015 Audi Q5 TDI
Ricosuave said:
was just wondering where the drain nipple is located...
Left front of car, where the lower radiator hose attaches. Push in on the knob, and trist a quarter-turn.

One addition to above instructions. You will still lose some coolant. Jack up the left side of the car to minimize loss.
 

Jetiwarrior

Well-known member
Joined
Oct 13, 2003
Location
Phoenix
TDI
2004 Jetta Wagon GLS
I just changed my coolant sensor and found a method to reuse the coolant without spilling any. First, I removed the intake box in order to give me maximum working space, then I shaped some aluminum foil under the sensor to lead the coolant into a funnel. Then, I attached plastic tubing to the funnel and drained the coolant into a pan located under the vehicle. Also, I did not have to jack up the car, drain any coolant, or remove the belly pan prior to starting. Finally, I removed the connector and the clip, and carefully pulled the sensor out part way until the coolant started flowing down the foil and into the funnel. Do not pull the sensor all the way out, or you will have a mess on your hands. It took about 2 minutes of holding the sensor part way until the coolant stopped trickling out. Then, I changed the sensor with the new o-ring and clip and then put the coolant back into reservoir. To filter out any dirt from the pan, I placed a folded paper towel in funnel. I found this forum quite helpful, and hope someone can benefit from this procedure.

Pictures below.




 

darryldeng

New member
Joined
Oct 6, 2008
Location
Oakland, CA
TDI
2004 Jetta
Didn't spill a drop....

I changed my Coolant Temp Sensor a few weeks ago and used a trick that I hope others will find useful. In addition to following the other useful hints offered in this forum, I use a new white colored kitchen trash bag strategically placed under the sensor housing to capture the leaking coolant. In my case, when I pulled the sensor free, the O-ring was stuck inside the housing and I had to go fishing after it. I didn't have to rush as the trash bag captured all of the coolant. After re-inserting the new sensor, I just gathered the trash bag and was able to reuse all of the coolant. The beauty in using the white colored trash bag is that you can see any debris in the coolant (held up to a light source) before reusing it. With coolant selling for $18 per gallon, a simple kitchen trash bag will save you money and time to clean up. The other recommendation I have is to remove the air filter housing which will allow ample room to get to the sensor.
 

bigfish313

Well-known member
Joined
Oct 30, 2007
Location
Berkeley California
TDI
03 Jetta wagon
coolant sensor

Awesome thread! Thank you everyone.
Just changed my coolant sensor.
I made a funnel out of a water bottle and 3 feet of 1" tubing.
It took me less then 15 minutes to change the sensor out.

$16.54 at TDIparts ...I didn't brake the clip or lose any coolant.
Thanks to all these great posts on these forums we can save a lot money:)
My wifey came in the house when I was Duct taping the funnel together and said "You're getting a little old for collage partys aren't you" LOL!!!




 
Last edited:

doscarson

Member
Joined
Oct 18, 2006
Location
Central Iowa
TDI
2003 Jetta - 285,000
O-ring size

I've found this all very interesting and useful. One bit of information for folks like me who lose the o-ring:


O-Ring Type
Standard
Cross Section Shape
Round
Width
3 mm
Inside Diameter
20 mm
Outside Diameter
26 mm
Material
Buna-N
Buna-N Type
Standard
Durometer
Hard
Durometer Shore
Shore A: 70
Temperature Range
-35° to +250°F
Color
Black
Specifications Met
American Society for Testing and Materials (ASTM), Society of Automotive Engineers (SAE)
ASTM Specification
ASTM D2000
SAE Specification
SAE J200

They can be purchased from your dealer, most motorcycle shops, and McMaster-Carr (part #9262K267 $6.18 for pkg of 50)
 

Snipely

Well-known member
Joined
Jan 7, 2003
Location
Chicago
TDI
2003 Jetta TDI Wagon, Indigo
Great thread, thanks everyone! I'm about to attempt this, but two questions.

1) 1. Open the top of the coolant overflow container to relieve pressure.

Won't fluid gush out faster with the cap off because air is now able to get in and displace it?

2) Did I read right that if temp sensor is bad, the temp gauge won't read? My temp guage is working! My CEL has been on for several months... (yes, I'm slow)

Thanks.
 

bigfish313

Well-known member
Joined
Oct 30, 2007
Location
Berkeley California
TDI
03 Jetta wagon
Snipely said:
Great thread, thanks everyone! I'm about to attempt this, but two questions.

1) 1. Open the top of the coolant overflow container to relieve pressure.

Won't fluid gush out faster with the cap off because air is now able to get in and displace it?

2) Did I read right that if temp sensor is bad, the temp gauge won't read? My temp guage is working! My CEL has been on for several months... (yes, I'm slow)

Thanks.
1) You should do this when the engine is cold so there shouldn't be to much pressure...After you open the cap you can close it again.

2) In my case the temp gauge was up a down all the time.
Now after driving awhile it stays right on 190...

BTW Does anyone else know if the temp gauge is suppose to be at 190 all the time?
 

SyntorX9000

Well-known member
Joined
Oct 17, 2008
Location
Indianapolis
TDI
2002 JETTA GLS TDI
EddyKilowatt said:
That's a great idea. The connectors on these cars are impressively well designed, but they're often smarter than I am... figuring out how to release the latch mechanism -- especially if the connector in question is shoulder-deep in the engine bay -- is often the hardest part of the job. :eek:

Maybe How-To's that include the words "just unplug the XX connector" should include "the XX is similar in style to the YY connector"...

Eddy

p.s. Eudaemonic -- two sensors, one housing.
Yeah, try the headlight connector...GEE firckin WIZZ...that thing is a real bear!
 

wetskier2000

Veteran Member
Joined
Aug 3, 2006
Location
NH
TDI
Gone: 05 Jetta GLS Wagon Current: 2015 GSW SEL 6MT
05 wagon temp warning light???

intermittent temp warning light on a PD. Guage reads normal and car drives normally. Is this the sensor??

thanks!

Rick
 

blandon

Well-known member
Joined
Aug 25, 2003
Location
Eugene, Oregon USA
TDI
2000 Jetta
Sensor Harness Connector

Has anyone ever had the electrical connector on the sensor get so irrevocably stuck that it can't be removed? I have (with tremendous effort) removed and replaced the sensor itself, managing to drain at least a gallon of coolant onto the floor in the process. And now, even now that it is loose and I can get both hands on it, I cannot budge the stupid connector off the old sensor. I am pushing on the tab to supposedly allow it to move - I've tried doing it with my thumb or with a flathead screwdriver, but I'm putting so much pressure on it that if the screwdriver were to slip loose I'd stab myself clean through the hand.

I really don't want to come this far only to be defeated by a g-dd--n plastic wiring connector (though that seems to be the way things go with this car).

Any suggestions?
 

blandon

Well-known member
Joined
Aug 25, 2003
Location
Eugene, Oregon USA
TDI
2000 Jetta
And a couple of follow-up questions, while I'm sitting here stewing in my own juices with rage...

1. How critical is it to wash the G12 off the various places it has leaked on? Will it rot out everything it touches as some people would have you believe?

2. Is it safe to drive the car maybe 5-10 miles with the temp sensor disconnected?
 

blandon

Well-known member
Joined
Aug 25, 2003
Location
Eugene, Oregon USA
TDI
2000 Jetta
Well, never mind... I eventually got the connector off, though it required a weird combination of prying on the connector joint while pushing on the tab with WAY more force than I was originally prepared to use (and more than any of the other connectors I tried first). So I refilled the coolant and ran down to the car wash for a quick hose-off of the engine bay. The bad news is that I'm probably looking at replacing my thermostat, since the sensor didn't seem to fix my problem.
 

paramedick

TDIClub Enthusiast, Vendor
Joined
Jul 29, 2001
Location
Versailles, Kentucky
TDI
2015 Audi Q5 TDI
blandon said:
Has anyone ever had the electrical connector on the sensor get so irrevocably stuck that it can't be removed? I have (with tremendous effort) removed and replaced the sensor itself, managing to drain at least a gallon of coolant onto the floor in the process. And now, even now that it is loose and I can get both hands on it, I cannot budge the stupid connector off the old sensor. I am pushing on the tab to supposedly allow it to move - I've tried doing it with my thumb or with a flathead screwdriver, but I'm putting so much pressure on it that if the screwdriver were to slip loose I'd stab myself clean through the hand.

I really don't want to come this far only to be defeated by a g-dd--n plastic wiring connector (though that seems to be the way things go with this car).

Any suggestions?
Push the plug TOWARD the sensor. Then push on the clip and pull it off. Most of the plugs of that type require this unintuitive approach.
 

JayT

Veteran Member
Joined
Dec 11, 2004
Location
Pennsylvania
TDI
Golf, 2003, Silver Beetle, 2013, Moonrock
Just for sympathy -- let me say that changing the CTS for me was a PITA the connector was a problem but I could not get the sensor seated again. I lost a rubber o-ring in the process.

;)
 

blandon

Well-known member
Joined
Aug 25, 2003
Location
Eugene, Oregon USA
TDI
2000 Jetta
Yep - I managed to get the old O-ring stuck in the hole too, without realizing it at first. What I thought was a very worn-down O-ring on the old sensor turned out to be just the tarnished brass on the sensor itself, so I spent a while trying to jam the new sensor + O-ring down on top of the old one, dribbling coolant all the while, before I figured it out.

That connector was what really had me fooled, though, even though (I thought) I knew how to disengage it. It just takes a lot of force to open the little tab, along with (as paramedick said) some reverse pressure first.

I would definitely recommend removing the old sensor, still plugged in, before trying to unplug the harness connector. It would have been even harder otherwise, or I would have broken the plastic clip that holds it in.

You live, you learn. Bruises heal and fingernails grow back eventually.
 

weirdajs

Veteran Member
Joined
May 13, 2008
Location
Junction city,KS
TDI
2004 New Beetle TDI
I just changed my Temp Sensor:D:p:eek: Thanks for the pictures that's all i really needed. $8.00 dollar Temp Sensor plus tools, a trash bag and one of those paper painting mixing funnels. 30mins later me very happy:):D Here is tip use one of those paper paint mixing funnels. Why because it has a screen on it to catch the dirt when filtering your coolant. Second is it cheap and can throw it away.
 

kafer65

Veteran Member
Joined
Jul 19, 2007
Location
TN
TDI
Early '06 Jetta 5M
Like wetskier my 04 PD has intermittant coolant temp light coming on. It happens the FIRST time I start it on a cold morning. It flashes red and beeps until I shut down at my destination. After that no indicator or beeps. Temp gauge works normally and the car runs well. My temp sensor area looks different than what has been described. In the same area I have a green sensor with wires coming out facing straight back coming out of a metal housing which looks to be a coolant conduit.
 

cmatheson78

New member
Joined
Feb 11, 2009
Location
Maine
TDI
2000 Green Jetta TDI
Coolant temp sensor...wrong part

Has anyone else noticed that many online suppliers are stocking the incorrect temp sensor? I have a 2000 Jetta TDI and had a very hard time finding the correct sensor. Many display an FAE two pin type sensor. The correct sensor has 4 pins. What gives?
 
Joined
Nov 18, 2005
Location
Florida
TDI
2003 Golf, 2004 Jetta wagon.
Thanks.

This forum is great!
Replacing the coolant sensor made my bipolar temp gauge work nicely. This is the third project that the TDI forum made easy. I'm so happy I sent Fred a small donation.
The hardest part was getting the electrical connection off the sensor. It's hard to pull the little release tab enough with your finger for it to release. After screwing around with it for too long, I finally took a small allen wrench and hooked the tab with the short end, tripped the catch and pulled the plug off. It came apart as easy as slipping out of a two bit hooker.
If anyone is still reading this thread, one poster mentioned the car "flooding" due to sensor malfunction. Can this be right?
 

shizzler

Veteran Member
Joined
Jun 25, 2005
Location
Ann Arbor MI
TDI
05 BEW Wagon
Just replaced the sensor on my parents 04 Jetta. Thanks to everyone who contributed in this thread!

Very easy process. I took my time and spent about almost an hour.

If there's any newbs still reading, here's how mine went.

I first jacked up the driver's side rear of the car to lean the coolant away from the sensor. Then pulled the air box for access, and used the white kitchen trash bag under the sensor idea. Neatly caught all the coolant (maybe .5 gal). This then allowed me to take my time, and simply pull the sensor out with the electrical connector still attached. The thing didn't want to release easily as installed (clip was facing away and down!), so pulling the sensor out of the block first made this MUCH easier. THe original O-ring also was still stuck in the block. I was glad to not be rushing to replace these things to avoid further coolant loss.

Code cleared.

Oh and Charlie, yeah I think if the engine thinks it's (very) cold, it will overfuel in an attempt to warm itself up. My parents were reporting more smoke and "stinkiness". Hopefully this will clear that up.
 

babydoll

Well-known member
Joined
Feb 20, 2009
Location
wv
TDI
01 jetta 5 spd 01 golf 5 spd cruze diesel 9 spd auto 17
hard warm starting

I have the same problem starts great, cranks a lot warm, the temp gauge goes too 190 after a few miles. is this the same sensor that caused the starting problems?
 
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