# Coolant Temp Sensor (CTS) on a 2000 Passat V6: Location and R&R



## 20th875 (Feb 11, 2004)

As mentioned in this thread, http://forums.vwvortex.com/zerothread?id=3811034, I was having cold start issues. Michael at Canyon Racer Motorsports in Mission Viejo, CA suggested it was the CTS as did one or two others on this forum. So, I got the parts and some direction on where it is located in the engine bay from some of you on here (spitpilot – thanks) and got busy. Also, I found this DIY helpful as well: http://www.tobio.info/passat/h....html, ***Before attempting this repair, please, let the engine cool. It would be even better to just do it in the morning so the motor is cold. Not only will you not get scalded, you most likely won’t loose a drop of coolant either (I didn’t). *** Now, this is a tough little part to get to. Especially for us very infrequent weekend mechanics. And even with my small hands, it still took about 20 minutes to get the sensor out. Then came the tough part.
The O-ring did not come out. And it did not look like, even with a good flash light and an inspection mirror, that there ever was one. But when I put the new sensor in, it would not sit low enough to put in the retaining clip. So I consulted Michael at Canyon Racer Motorsports again and he assured me there must be an O-ring in there still if the sensor would not sit low enough to clear the clip (VW calls this a “spring”). So I went back out in the garage and looked at it some more. The O-ring was indeed hiding in there. I could not feel or see it with an inspection mirror. Probably because it had disintegrated and was about half of its normal height and was square now instead of round. Once I started scraping, it was apparent that it was still in there. Had to use several long objects including my fingernails to scrape it all out and it took more than an hour to get all the old O-ring out and two tries before the sensor would sit low enough for the clip to hold it in place. What a stupid location for that part. My small hands had a pretty hard time and are a bit banged up. But it’s done now. 
If you are easily intimidated, I would leave it to a mechanic. If you are in for an adventure, go for it. Just make sure you have some basic abilities and tools and more than an hour to do the R&R. If the washer had not have been so conformed to the housing and had come out easily, it would have taken me 30-45 minutes total to do this job. But it really turned into an affair trying to find out why the new sensor would not sit low enough for the clip to hold it in place. Be aware of this when you attempt it.
Now, placement of the sensor and the parts needed. Some of the following comments are from others and I would not want to give the impression that I figured all of this out on my own. But that’s really what the Vortex is supposed to be about, a knowledge exchange. Thanks to all of the various comments and posters that helped me get through this job. The sensor is located behind the passenger-side cylinder bank. Just take off the intake hose that runs from the air box to the intake and the sensor is below it. Taking off the engine covers will also help and is the easiest part of the job. Now look for a connector with four pins that is secured by a clip. It sits about six inches below the top of the passenger-side valve cover. The clip fits in grooves in the housing to hold the sensor in place. Once you find the housing with the clip, you’ve found the culprit. You need to use a long screwdriver to pry the clip out, then with the connector still attached, just remove the sensor (and hopefully with little drama, the o-ring washer too) and then detach the connector by using a screwdriver to disengage the ear on the side of the connector. Now, check the housing is clean and also make sure that pesky o-ring washer is out and then install the new green-top sensor with o-ring into the housing. Here’s a great tip I learned for this job. Tie your clip to a long piece of thread (I left the thread attached to the spool), because you will invariably drop it in this very tight space and it will go into never-never land somewhere on top of the transmission and you’ll never see it again and thus need to buy a new one. (I lost a ¼” drive 10 MM socket and it’s as if it went into a black hole and there’s not much room to look for it anyway.) If the sensor is in all the way, the clip should go right in, not much effort required. Then you just need to reattach the connector and put the breather hose and engine covers back on and you are done.
Parts needed: coolant temp sensor 059-919-501-A $30.43
O-ring washer (seal) N-903-168-02 $1.51
Clip (spring) 032-121-142 $0.64
Not a cheap fix at $35.43 including tax (VW Dealer), but the car now runs normally and I have the satisfaction of doing it myself and saving the really tough stuff for Michael at Canyon Racer. I paid about $5.00 for the same parts three or four years ago for my 20AE. My how inflation has reared its ugly head (more like the stealership has gotten greedy.) So, this is all you should need to know to get this job done and make sure to top up your coolant when you are done if necessary. I hope this helps someone save a few bucks and avoid the pitfalls inherent with this job. Cheers.


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