Coolant temp sensor popped out

ultravorx

Well-known member
Joined
Apr 27, 2011
Location
Ellington, CT
TDI
2004 Golf PD
Coolant temp sensor popped out *Possibly fixed*

So, after completed a 605 mile tank, I finally had to get more fuel. On my way from the pump, I got on the car a bit to "clean her out". I had noticed that there was some white smoke behind me, along with black which was odd. I am Kerma tuned BTW.

At this point I noticed my coolant temp was at 0. I figured something was up, a minute later my engine temp light went on. At this point I shut the car off and pulled over safely (yes, in that order).

I found that I had lost a lot of coolant, and the source of the hole was the coolant temp sensor had popped out of the engine block, and the clip was still in place.

Has anyone seen/heard of this issue? I had to get a new sensor because the O ring went along for the ride with the coolant.

Its not a big hassle to put it back together, its the cost of the GL12 coolant which hurts.

I managed to reseat the sensor and clipped the holder back in, which gave me a positive snap as it seated.

Is this something I should be worried about, or could it have been a fluke since the last time I changed the sensor about 4 weeks earlier?

Any thoughts would be great!

Frank
 
Last edited:

lmtman

Well-known member
Joined
Oct 10, 2010
Location
Hydro, OK
TDI
02 Jetta TDI 5sp
You should be alright. I replaced mine a few weeks ago and could'nt get it to seat. I finally figured out that the old O ring stayed in there when i pulled the sensor out. Since then i have not had any trouble.
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
So, after completed a 605 mile tank, I finally had to get more fuel. On my way from the pump, I got on the car a bit to "clean her out". I had noticed that there was some white smoke behind me, along with black which was odd. I am Kerma tuned BTW.

At this point I noticed my coolant temp was at 0. I figured something was up, a minute later my engine temp light went on. At this point I shut the car off and pulled over safely (yes, in that order).

I found that I had lost a lot of coolant, and the source of the hole was the coolant temp sensor had popped out of the engine block, and the clip was still in place.

Has anyone seen/heard of this issue? I had to get a new sensor because the O ring went along for the ride with the coolant.






I have had this issue before shortly after I first purchased the car and decided to replace the temp sensor. I din't know much about the car, and it was frustrating when it happened three times to me. I think I remedied it by using a thicker O ring, and actually getting the plastic retaining clip in the correct place. The sensor seems to wobble a bit too much for my liking, and is a poor design IMO which was helped by using the thicker O ring. Good luck, and you may have to do what I did-carry some extra distilled water/coolant with you for emergencies especially after replaceing that temp sensor until the issue is behind you.
 

ultravorx

Well-known member
Joined
Apr 27, 2011
Location
Ellington, CT
TDI
2004 Golf PD
So, after completed a 605 mile tank, I finally had to get more fuel. On my way from the pump, I got on the car a bit to "clean her out". I had noticed that there was some white smoke behind me, along with black which was odd. I am Kerma tuned BTW.

At this point I noticed my coolant temp was at 0. I figured something was up, a minute later my engine temp light went on. At this point I shut the car off and pulled over safely (yes, in that order).

I found that I had lost a lot of coolant, and the source of the hole was the coolant temp sensor had popped out of the engine block, and the clip was still in place.

Has anyone seen/heard of this issue? I had to get a new sensor because the O ring went along for the ride with the coolant.






I have had this issue before shortly after I first purchased the car and decided to replace the temp sensor. I din't know much about the car, and it was frustrating when it happened three times to me. I think I remedied it by using a thicker O ring, and actually getting the plastic retaining clip in the correct place. The sensor seems to wobble a bit too much for my liking, and is a poor design IMO which was helped by using the thicker O ring. Good luck, and you may have to do what I did-carry some extra distilled water/coolant with you for emergencies especially after replaceing that temp sensor until the issue is behind you.

I did notice that i did get a nice "positive" click when I reinstalled the clip. Im just afraid its going to happen again when I really step on it! Maybe I only try it around my house so I dont get stuck again.

So it seems that this isnt a coomon problem.

Frank
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
I did notice that i did get a nice "positive" click when I reinstalled the clip. Im just afraid its going to happen again when I really step on it! Maybe I only try it around my house so I dont get stuck again.

So it seems that this isnt a coomon problem.

Frank







Keep us posted on how it goes
 

ultravorx

Well-known member
Joined
Apr 27, 2011
Location
Ellington, CT
TDI
2004 Golf PD
Happened again, may have found issue

So, after a nice long 500 mile trip, it happened when we got home.

I was driving down the street to softball, and I decided to give it a quick romp from a stop. Right as Im going down the street I see smoke from the engine bay. Clip and o ring are gone!

I finally start searching with a flashlight and found the clip, but no o ring. So i was off to advanc autoparts for a 3rd sensor (since its the only thing open on sunday which comes with an o ring.

This time, I changed the sensor out. Last sensor was from auto zone.

What i noticed is that the sensor from auto zone and advance auto parts were different. The metal ring on the sensor I had issues with is cupped, while the new sensor I got with the o ring is not.

In the picture, the sensor from advance auto parts is on the left (good one), and the one from auto zone is on the right (one that keeps popping out). You can see a definitive difference.


The cupping near where the clip makes contact is possibly why the sensor pops out under heavy load. Im also going to VW for a new plastic clip just to be sure, but it does look like the sensor design may be the issue.

Frank

 

BolaB4V

Veteran Member
Joined
Dec 30, 2007
Location
Northern NY
TDI
1996 passat tdi wagon, 97 F-150 XLT 4x4, 99.5 Mk4 Jetta VR6/5M
If its next to another sensor in the block the clips can infringe on each other, such as a AC cut off sensornext to the CTS. In that case id turn one of the sensors 90 degrees clockwise and install the pin and clip.
 

Verglass0077

New member
Joined
Sep 7, 2023
Location
Los angeles
TDI
Volkswagen 2012
Ik i know this is a very old thread... nonetheless id figure me telling my experience & (what i did to resolve it) would help someone as this thread helped me ... sooo looking at franks picture i figure that my sensor since oem never changed was the problem .. however after further analysis of the sensors positioning - as well as the o ring & c clip i noticed that only one side was completely uniform () circular around the plug whilst the left side was skewed slightly ... long story short before buying a new temp sensor id suggest buying oem o rings and clip from dealer as well as the g12 fluid -- and play with fitment -- long part--- (use the coolant to lubricate the ring & temp sensor) and when clipped try to pull it out (this will test if the fitment is correct) as it took me 3 tries and 3 o rings fortunately their cheap at my dealer around 7$~ for 2 - now while u dont want to put too much pressure the object is to put uniform pressure as well as hold it whilst putting the clip in (& again trying to pull it straight up will verify if youve fitted it correctly.. the first 2 times i didnt do this and the temp sensor kept popping out ..... youll know when youve fitted it correctly because when u go and try to pull it straight up it wont budge and the wiring (on my car its a black casing 2 pin female) will lift slightly indicating snug fit.. & i seen someone talk about babying the throttle/acceleration .. i instead used that as a test.. i put it in sport mode & went around the corner a few time flooring it ... no popped out sensor & no white smoke from hood. Hope this helps someone.. - will edit if any troubles later .
 
Top