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Discussion Starter · #1 ·
Im getting the common "STOP check coolant" warning on my 1.8T AGU when i start my car from cold in morning (hot or cold day) after switch off and on this goes away, been told its either

1. Expansion bottle level sensor ??( VAG never herd of this but its been mentioned on this forum??)

2. Temperature Sender (very common), I beleive more to do with Temp guage issues.

3. New expansion bottle

Someone with same probs please let me know how you got rid of it! its driving me mad...PS the water pump has been changed!

Thanks
 

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Mine was the sensor in the bottle, though it comes as one unit, so get yourself a new bottle. Think it was about ?8. Then if you're lazy draw the coolant out of the old bottle with a turkey baster (not sure I've spelt that right), pop the new bottle in (3 screws, 2 pipes), then pop the coolant back in the new bottle. Easy!
 

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i get the signal flash up just the water symbol and a buzz for 3 seconds in morning when i start the car and also when i leave car standing for a few hours .
 

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Discussion Starter · #5 ·
Thanks il try that, at least I know someone has chaged the bottle, its only ?8 from VAG..not bad. strange but its not occoured last 2 days?? but anyhow annoying bloody sound!

Thanks
 

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Mine came up with the same warnin so i put VAG COM to it and found out that it was the temp sender knackered only a couple of quid from the local stealer

cheers
 

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Mine used to do the same thing when cold and then the warning light would go off when warmed up. I topped up the water and now it's fine
 

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Mine has also come on - 2000 TDI 110 bhp 58k miles and was due to low coolant. Topped up and it is fine. However, why does the coolant level drop over time?? - I have not found any signs of weeping joints or leaks. I can only think that it is getting into the engine - and the oil is fine.

What is an acceptable rate of coolant loss??

TVMIA
 

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Discussion Starter · #10 ·
im not sure what an acceptable rate is, mine comes on and goes off when i drive off! I think its the bottle, but then im not sure as VAG-COM has not produced any fault codes. I will top up again and see how long it goes for., how often are you topping up Colin
 

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Discussion Starter · #11 ·
Surely enough this has come up again today, so i switched the car off and on again then it goes away, my coolant is above the MIN level sort of half way to the MAX, where should the level be kept before this stupid sensor kicks in? I now suspect the bottle (although coolant level does drop ever so slightly, anyone know how much loss is acceptable? (its a 1.8T with new water pump)

TIA
 

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Yep, I have the same problem. My temperature gauge hasn't worked for a while now, but sometimes it just starts working for a second and then dies again. Then just recently, the coolant level light came on in the mornings, just switched the car on and off and it is fine again. Happens every morning pretty much.

Do you think the problem with the temp. gauge not working and the coolant level light coming on are connected ?

Thanks
Ryan
 

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You will find that if the guage does not work then it will be the sensor.

If you get the warning beep then check the level , if the level is low it is doing its job and warning you.Top it up but only when cold.

Check every morning before you leave for a couple of days just to keep an eye on it.

If it does drop the most common problem could be with the rad fan switch with a slight leak.

With the G12 or G12+ this will leave a colourfull crusty residue on the switch or point of leak.

If there is no problem with the level it will be the sensor.Very common problem with VAG cars and would require a new expansion tank.

They are not expensive and also could be worth replacing the cap at the same time as the seal can go on them too.

All worth keeping an eye on as if the level does drop or your reading on the guage is incorrect then you can overheat.

If this happens you will have a very good chance of doing the head gasket.

Ooops that can be very expensive.

So be warned

Sarah
 

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Yeah mate. I just had all new suspension fitted took it for a bit of a blast and (" STOP" Check coolant level). flashed up

Ive just changed the coolant sensor (?27) from the STEALER DEALERS, took it for a blast and same appeared ive left it running but the fan isnt working(wouldnt you thought that id have checked that 1st).

Rung the dealers for a new fan switch they range from ?14 - ?17 so not too bad.

Hope this helps!!!
 

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Discussion Starter · #15 ·
You will find that if the guage does not work then it will be the sensor.

If you get the warning beep then check the level , if the level is low it is doing its job and warning you.Top it up but only when cold.

Check every morning before you leave for a couple of days just to keep an eye on it.

If it does drop the most common problem could be with the rad fan switch with a slight leak.

With the G12 or G12+ this will leave a colourfull crusty residue on the switch or point of leak.

If there is no problem with the level it will be the sensor.Very common problem with VAG cars and would require a new expansion tank.

They are not expensive and also could be worth replacing the cap at the same time as the seal can go on them too.

All worth keeping an eye on as if the level does drop or your reading on the guage is incorrect then you can overheat.

If this happens you will have a very good chance of doing the head gasket.

Ooops that can be very expensive.

So be warned

Sarah
Thanks for the reply, Yes I would agree sensor is working (simple test is to unplug it from the expansion bottle and surely enough the annoying beep sounds (open circuit) However the level is above min and half way to Max seem I need to be almost near MAX for it to be happy? When should this sensor cut in...im looking to change that bottle and also get a pressure test done.
 

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You will find that if the guage does not work then it will be the sensor.

If you get the warning beep then check the level , if the level is
low it is doing its job and warning you.Top it up but only when cold.

Check every morning before you leave for a couple of days just to keep an eye on it.

If it does drop the most common problem could be with the rad fan switch with a slight leak.

With the G12 or G12+ this will leave a colourfull crusty residue on the switch or point of leak.

If there is no problem with the level it will be the sensor.Very
common problem with VAG cars and would require a new expansion tank.

They are not expensive and also could be worth replacing the cap at the same time as the seal can go on them too.

All worth keeping an eye on as if the level does drop or your reading on the guage is incorrect then you can overheat.

If this happens you will have a very good chance of doing the head gasket.

Ooops that can be very expensive.

So be warned

Sarah
Thanks Sarah, very helpful. getting the sensor replaced on Saturday,
and atleast that will fix the gauge. After that, I'll check to see if
the collant level light flashes again, and if it does, i'll assume it's
the expansion tank sensor thingy, and I'll get that replaced !

Cheers

Ryan
 

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You will find that if the guage does not work then it will be the sensor.

If you get the warning beep then check the level , if the level is low it is doing its job and warning you.Top it up but only when cold.

Check every morning before you leave for a couple of days just to keep an eye on it.

If it does drop the most common problem could be with the rad fan switch with a slight leak.

With the G12 or G12+ this will leave a colourfull crusty residue on the switch or point of leak.

If there is no problem with the level it will be the sensor.Very common problem with VAG cars and would require a new expansion tank.

They are not expensive and also could be worth replacing the cap at the same time as the seal can go on them too.

All worth keeping an eye on as if the level does drop or your reading on the guage is incorrect then you can overheat.

If this happens you will have a very good chance of doing the head gasket.

Ooops that can be very expensive.

So be warned

Sarah
Thanks for the reply, Yes I would agree sensor is working (simple test is to unplug it from the expansion bottle and surely enough the annoying beep sounds (open circuit) However the level is above min and half way to Max seem I need to be almost near MAX for it to be happy? When should this sensor cut in...im looking to change that bottle and also get a pressure test done.
Yes replace the bottle.

It is a warning so it will cut in BEFORE it gets to the minimum as it wants to warn you that it is getting low.

You tend to find that when it goes down it will beep when there is nothing wrong with the level.

Top it up to max and if it continues to beep then it means it is faulty.

You could not say it is faulty if your level is low.

But when you know what to look for you can keep an eye on it.

Oh and I am sorry did forget to warn you of the rad fan switch.

Another one to keep an eye on.

Sarah
 
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