Coolant Temp Sensor

**ecjr173** · 12-02-2008 10:05 PM

I want to replace the sensor but i cant seem to find it. I know its between the block and the firewall but i cant see it. Do i have to remove some thing first or am i just an idiot. I am a noob but i just cant see it. I went to a4mods and followed their directions but no luck finding it. If any body has any pics or diagram it would help me alot. Thanks

**BryMFL** · 12-02-2008 10:31 PM

It's the only thing with wires coming out of it on the back side of the engine, well there is the chain tensioner but it runs parallel with the back of the motor and the wire for that is poking out on the right side. If you see the metal round tank looking thing it's just to the right behind it. It should be green or black

**EuroTrA4sh** · 12-02-2008 10:49 PM

i replaced mine tonight...drove back from school and parked in the driveway and there was alot of steam/smoke coming out... looked at my coolant and it was empty :( i gotta figure out what happened tomorrow hwen the car is cooled down... it's in the back, next to firewall. it's a PAIN to get to it... so yeah thats my experience :/

**jursch2211** · 12-02-2008 11:20 PM

its a little difficult to get to if you have large hands. Get a long neck screwdriver and pop out the retainer clip from the side and beware that coolant will leak out. after that it might make it easier to pull the wire harness off and then just replace with the new on. Oh and just a note but the retainer clip doesn't have go back in the same way. It will make it easier if you need to replace or remove the sensor a different time.

**thursdaysstrike** · 12-03-2008 02:07 AM

Originally Posted by EuroTrA4sh

i replaced mine tonight...drove back from school and parked in the driveway and there was alot of steam/smoke coming out... looked at my coolant and it was empty :( i gotta figure out what happened tomorrow hwen the car is cooled down... it's in the back, next to firewall. it's a PAIN to get to it... so yeah thats my experience :/

your in euromama?

do you know a guy named kevin tang? drives a GTI

**MJM Autohaus** · 12-03-2008 02:18 AM

They're a PITA to install and as much as I like A4mods (great DIY site), their directions aren't the easiest to follow if you don't know what you're looking for. What we use here with good success when doing them (A4mods should mention this) is to use a mirror back there so you can see what you're doing. Trying to do it without a mirror is darn near impossible, IMO. Your girlfriend's nose-powder mirror would work fine.

**gtimart** · 12-03-2008 09:14 AM

I chose to remove a couple of hoses that block the view. I even unplugged my four coilpacks to be able to move away some wires to get a better view. I think it's 100x easier to do that way, and probably not more time-consuming either. I actually saw the sensor and the clip I had to work on.
As someone else said on the forum, work on a cold engine and open your coolant tank first to relieve pressure. I had no coolant leak at all when I did it.

**Audi Skate Snow** · 12-03-2008 09:19 AM

http://www.audiworld.com/tech/eng66.shtml

here you go, its not as hard as people think.

**dougyfresh** · 12-03-2008 09:24 AM

Make sure you replace the o-ring. I've found a tiny bit of silicone grease on the o-ring helps seat it properly and make installation easier.

I am currently replacing the o-ring in my coolant sensor on the lower radiator hose. After removing my belly pan Sunday night I realized my coolant leak is through that sensor. Damn stealership wanted $3 for the o-ring.

and I just paid $15 for four Nord-Lock washers today

These little fasteners add up in cost since no one carries everything I need locally as well as everyone online doesn't have everything I need. So, I've got stuff coming from like 5 different places. 5 different shipping costs. Just a little frustrating..

**Audi Skate Snow** · 12-03-2008 09:33 AM

Originally Posted by dougyfresh

Make sure you replace the o-ring. I've found a tiny bit of silicone grease on the o-ring helps seat it properly and make installation easier.

I am currently replacing the o-ring in my coolant sensor on the lower radiator hose. After removing my belly pan Sunday night I realized my coolant leak is through that sensor. Damn stealership wanted $3 for the o-ring.

and I just paid $15 for four Nord-Lock washers today

These little fasteners add up in cost since no one carries everything I need locally as well as everyone online doesn't have everything I need. So, I've got stuff coming from like 5 different places. 5 different shipping costs. Just a little frustrating..

100% agree... if you dont seat it right then your going to have a hell of a time putting the retaining clip in. most places that sell the sensor come with the o-ring, but i think the o-ring, sensor and clip is like 25 bucks shipped from most places.