Coolant temperature sensor location.

The Colonel

Member
Apologies for repeating other threads but I’m desperate to get a definitive answer. Can anyone please tell me the location in easy vocabulary of the coolant temperature sensor. In my latest attempt to sort the car out I’m trying changing the sensor. I read that starting issues could be down to the sensor being faulty, and confusing the air/fuel mixture.

There’s so much pipe work and so little space I’m getting frustrated with the car. I have a 54 plate 1.6 se fsi. Any advice would be gratefully received and prevent me from abandoning the a2 altogether and going back to a basic old car.

Thanks.
 

BiggDogg

Member
Here’s a picture of the coolant sensor (green) with the wiring, cylinder head and EGR pipe removed. It fits into the thermostat housing which mounts to the cylinder head above the gearbox. Photo is a recent one of my project FSI. Remember to push the connector onto the sensor before pressing the tab which unlocks it, then pull it off whilst still pressing the tab. This method avoids breaking the connector locking tab by compressing the rubber seal a little to allow the tab clearance to unlock.
Good luck!
Matt


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BiggDogg

Member
IMG_5175.jpg



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The Colonel

Member
Here’s a picture of the coolant sensor (green) with the wiring, cylinder head and EGR pipe removed. It fits into the thermostat housing which mounts to the cylinder head above the gearbox. Photo is a recent one of my project FSI. Remember to push the connector onto the sensor before pressing the tab which unlocks it, then pull it off whilst still pressing the tab. This method avoids breaking the connector locking tab by compressing the rubber seal a little to allow the tab clearance to unlock.
Good luck!
Matt


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Thanks for the reply. Do I need to remove all that pipe work and wiring to access it or is it a case of working blind and feel and hope?
 

BiggDogg

Member
There are 2 challenges.
First you need to take the c-clip out and that might mean taking the EGR pipe off first, I can’t completely recall (apologies if this is wrong). The bolts for that are the 12 (?) point female spline type.
Second the sensor can be fitted at any angle so accessing the tab to unlock it may be difficult. If you undo the c-clip first then the sensor and wiring can both come out together.

Don’t forget to change the o-ring and ideally use new metal gaskets for the EGR pipe if you have to take it out.

Coolant is going to go everywhere so best to drop the undertray and drain the system (at least partly) into a container. You might want to take the opportunity to change the coolant if it is old.




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Nye

Member
I thought my temperature sensor had failed recently but as I'd been ferreting about in the area of it fixing a coolant leak I decided to check the connector plug. Sure enough, a wire had come out of the connector (which is relatively easy to remove, once you find it!). I'm hoping this should be easier to fix than replacing the sensor.
 

BiggDogg

Member
Colonel, I see on your other post you’ve found the sensor location so this will likely come just too late. Assuming your starting problems are cold, then you could disconnect the wire from the old sensor and connect it immediately to the new sensor and try starting it like that-which would tell you if the old sensor is the cause of the starting problem or not, and therefore whether to go to the hassle of completing the job. I use a 3” mirror too for these jobs, I can get a decent image with a bright head torch.


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Crgwal

Member
I didn't read all the posts.

I have a 1.6 FSI I changed the Temperature sensor without removing the pipe above it. It's fiddly yes but it definitely can be done.

FYI
 
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