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Discussion Starter · #1 ·
Hi,

I noticed my temp gague suddenly drop from 90 degrees (10 mins into my journey) down to the line just before 90, then back up to 90, then to 0 and then back up to 90. it then stayed at 90 for the remainder of my journey (about another 20 mins). This is the first time i've ever noticed it doing it.

The coolant level seems ok. I've seen posts about a common problem with the temp sensors on VW's. Any ideas?

Thanks in advance.
 

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Most likey to be the CTS (coolant temperature sensor), but could possibly be the thermostat or other underlying issue. A quick scan on VagCom usually helps to diagnose the issue.

If it is the CTS you require give me a shout as I have a brand new one for sal,

Luke
 

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Discussion Starter · #3 ·
VagCom costs a lot of ££££ though!

I've only had the car 10 weeks! I've just spanked loads of ££££ having the turbo replaced. It's one thing after another with newer VW's!! I thought they were meant to be reliable? I had an A-reg Mk2 back in the late 90's and NOTHING went wrong with that baby!

Are CTS's easy to replace? As in, would I be able to change it myself?
 

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Very easy to do...5 minute job.

IIRC there were a couple of guides floating about, but once you have located the secsor (under the lower engine cover) it is simply a matter of removing the plastic wiring clip, remove the plastic clip and pull it out. Just make sure it is done when the engine is ice cold (i.e. left overnight).

As for reliability...the MK4 seems to have a few common faults, but nothing major.
 

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Discussion Starter · #7 ·
Has anyone out there changed one of these CTS's before? it looks like a right fiddly job to do!?
 

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It's a 15 minute job - just dont do it in the carpark whilst your on your break as you will find yourself dropping the sensor somewhere in the undertray and having coolant gush everywhere...then having to risk driving home with low coolant because its dark and you cant see where the £30 sensor you have just dropped has gone and hope its still there when you get back.......

Yes been there done that lol
 

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Discussion Starter · #9 ·
Hmm......cheers.

Is the CTS just held in place with that C clip? Or doesn it screw in?

One of my annoying mates at work (who of course knows everything about everything) broke the C clip off apart from one tiny piece at the back of it!

I don't want to drive it home only to find that the CTS has blown out under pressure!
 

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depends how hard its pushed in. It sounds risky if you ask me, dont want the water pressure to blow it out whilst driving lol. Its a bad design.
 

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Seconded...I personally wouldnt want to risk it.

Send the dude who broke it to VW to buy a new clip, or pay for your taxi costs...
 

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Discussion Starter · #14 ·
Part of the clip is still in place, but 75% of it has broken off!

I'm going to have to risk it! i'll just have to drive V slowly and keep the revs right down!
 

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Make sure you have the AA or RAC or Greenflag or whatever on speed dial :) - good luck! keep us posted how you got on.
 

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Discussion Starter · #16 ·
Yep, AA cover at the ready!

I guess the temp will shoot zero if it does blow out!? And the heater will go cold as the water drains! Then I'll be pulling straight over!
 

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If your water comes out , the dash will light up like a christmas tree and the temp guage will got right up to red!!!, if you keep running it the gaskets will warp and you could even crack the head and block. Happy driving :)
 

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Discussion Starter · #19 ·
I managed to bodge the broken clip back on. That got me to GSF to pick up a new clip and a couple of spares just in case. 40p each! Now to wait for the engine to cool down before replacing the clip. No problem with the temp gague on the way home either!? I think I'll tackle the sensor at the weekend in daylight unless it plays up again before then!?
 
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