Yeah, it's man's work :ROFL:

Sounds a bit of a bugger to me... :rolleyes:

DONE IT! Good job I didn't start replacing Lambdas, quick blast and another VAG COM scan and the fault codes and engine management light have gone. Now fingers crossed it passes its MOT tomorrow or I won't have enough money for its service (1.5k miles/2 weeks away!) :rolleyes:

Amar, I know this is an old thread, but what engine was this on, and what was the trick to replacing the sensor?

I'm getting some occasional starting oddness (FL S8) and a regular warning (cleared by VCDS but comes back) that the coolant sensor is giving intermittent bad readings.

Also, do you have the part number?

Edit: Doing a "rummage" online it looks like it could be a very common part (059919501A) across the whole VAG range, or is it A8/S8 specific?

Here's a US supplier listing the D2 S8, but plenty are available locally for about £15 including clip and seal. http://www.europaparts.com/coolant-t...59919501a.html

And just had a quick look and I can see it's a green one in there, not sure about replacing it myself though.

HP, I'm sorry but rally cannot remember the method although I'm 70% sure it were on my FL 2001 S8.

OK thanks Amar. I've ordered one online complete with clip and seal and will have a look when it arrives.
The car is due in to the garage week after next anyway for some other work (mainly a leaking gearbox output seal) so I'll get them to fit it if I can't.

Fitted this morning with some help from a more experienced friend who, more importantly, has smaller hands than me. :cool:
Only took about 20 minutes in the end and seems OK so far - codes cleared, not returned, behaves OK and temp gauge acts normally. +++

No particular tricks, just looking carefully and working out what and how to do it. Start with a stone-cold engine and DON'T remove the expansion tank cap:
1. Removed engine cover
2. Removed air pipe - 2 jubilee clips to loosen, one each end (don't try to split in the middle). Take off completely the jubilee clip at the manifold end as it's on a rubber moulding that gets in the way rather and without the clip you can push it aside a bit when necessary for better access.
3. Took off plug lead which is a bit awkward to get at. This was tricky as it wasn't clear how to release the catch so liberally applied WD40 first. Basically you press in the small catch that is surrounded by a plastic rim (so lifting the latch further down) and wiggle the whole plug upwards.
4. Note carefully where the retaining horseshoe clip is located then pull it out sideways (towards offside) with long-nose pliers.
5. Wiggle the sensor until it comes out. Mine seemed to rotate OK but needed a good wiggle and strong pull with pliers to release. No coolant escaped, but it was visible.
6. Extract the sealing ring - this needed a poke about with a thin screwdriver to unseat.
7. Clean all around and pop the new ring in, ensuring it's seated properly.
8. Insert new sensor - it probably won't go straight in as with a new sealing ring it's a tight fit and applying pressure with fingers is near-impossible in the small space. We pushed it down with the end of a (rubber) hammer handle easily enough. Don't use anything too solid or you risk damaging the wiring socket. MAKE SURE the sensor is fitted so that the retaining clip for the wiring plug will be accessible for removal!
9. Slide new horseshoe retaining clip back in. Bit of a swine this as it's difficult to grip and see and needs to align with slots you can't see. We had the small-fingered one holding it with me using a light and giving "golden shot" style instructions (down a bit, left a bit etc. etc.). Luckily little force is needed if the sensor has been seated first.
10. Refit the wiring plug.
11. Refit air pipe and secure, refit engine cover.

The actual sensor only cost me £7.50 delivered and seems to be a standard VAG unit.

So far, so good. 2 days and a selection of short journeys with no problems and no new codes.

Just the intermittent "gear recognition signal" one that I ought to have investigated sometime. :o

A bit late in responding to this, since I replaced mine around the end of August, but very easy when you have great instructions like this, so a big thanks.

Just an update for this thread with a little tip. ;)
I did this again today, actually reversing what I did in August last year. :eek:
The replacement sensor failed, even throwing an error shown by VCDS, and was causing severe starting problems. So I put the old one back.

The problem with the old one was that it showed a low temperature on the dash, but otherwise caused no problems. :Confused:
Now I need to get a fully-working one and go through this process yet again.

I did this alone, without the help of the "small-fingered one" and getting that clip back in took ages! I managed by manipulating it with one hand and pushing it in with a long screwdriver held in the other.

The tip? Tie a long piece of thin twine around the "loop" bit of the clip and add a bit of tape to stop it slipping around. Just tape it on somewhere or hold the end in your mouth.
Then, when your cramped hands lose grip, it won't disappear forever behind the engine. +++