Idiot light came on this morning

CanadianALH

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2002 Jetta 5spd 2006 Jetta DSG (wifes)
2002 Jetta ALH had my car plugged in over night as it was a little chilly started up this morning no problem, pulled onto the highway 2 min later and about a min after that the coolant light started blinking, temps were cold but I pulled over shut the car off started it again no light the rest of the drive. I am going to let it sit 2pm and then I'll check the level I did some reading and it sounds like my coolant may be shrinking in the cold so if it's a little low I will add some. Now the coolant question, how good are the odds I have G12? I don't want to drain and flush the system right now as I don't have time. If it says G12 on the bottle I will add more G12. How likely is it a sensor or a bad connection?
 

Zak99b5

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2003 Jetta TDI
If you don't need to add much, you could just put distilled water in it to make up the level. Ratio won't be thrown off much at all, assuming you haven't been adding only water in the past.
 

CanadianALH

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If you don't need to add much, you could just put distilled water in it to make up the level. Ratio won't be thrown off much at all, assuming you haven't been adding only water in the past.
It gets to -40 here i understand what you’re saying but I honestly don’t want to risk it. I’d rather toss a little all makes coolant in there. I need to see if its a little low first.
 

BobnOH

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central Ohio
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New Beetle 2003 manual
Bit of research revealed blinking coolant light is an indicator of low coolant. Could need a bit added, but a couple members reported fixing it by cleaning the probes on the sensor inside the bottle.
Course could also be bad sensor or wiring/connects.
 

CanadianALH

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I also read that. Over on vortex I saw most of the guys saying bad sensor. Can you remove the sensor and clean it? I don’t get a warm and fuzzy feel about cleaning it in the reservoir.
 

MrCypherr

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The sensor on the bottle is part of the bottle. Unless you can get some cleaner in there which I dont think would work, you'd need a new bottle.
 

CanadianALH

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The sensor on the bottle is part of the bottle. Unless you can get some cleaner in there which I dont think would work, you'd need a new bottle.
This is what I was afraid of. I will look at level and if it’s low I’ll add a little. If not I’ll assume sensor and look at buying a new one.
 

CanadianALH

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It's the sensor that gets fuzzy ;) A toothbrush works fine, no need to replace the ball.
Just scrub it a little? I guess all the stuff that is on it is already there so it can't really hurt the system.
 

jayb79

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Exeter,NH
It's simply 2 small silver-colored rods sticking into the coolant when they aren't covered with coolant the light flashes. Clearly visible when you unscrew the top. No need to mess with cleaning them if the coolant is low unless they are covered with something.
 

CanadianALH

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It's simply 2 small silver-colored rods sticking into the coolant when they aren't covered with coolant the light flashes. Clearly visible when you unscrew the top. No need to mess with cleaning them if the coolant is low unless they are covered with something.
Awesome! Any idea what the resistance is supposed to be cross them? Or is it a captive type? I could test it and see if there is a fault with the sensor.
 

BobnOH

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central Ohio
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New Beetle 2003 manual
Simple, when the probes are under coolant, they connect. Suck out bit of coolant if necessary and clean the contacts, a bit of alcohol on the brush. Resistance would be high when dry, if not, could be some wire issue.
 

CanadianALH

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There is definitely lots of coolant in there. So I’m thinking sensor wasn’t happy this morning. I’ll keep my eye on it
 

JordanTr

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1996 B4V x3, 2006 Dmax, 2005 Allroad, 2005 BHW
My B4 did this on a cold morning a few weeks ago but the coolant was a bit on the low side so a top up with G13 was all it took.
 

CanadianALH

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If it does it again I will. Hasn’t done it all day since. The weird part is it didn’t do it that entire cold snap.
 

CanadianALH

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Do your research. Some non-spec coolant can react chemically with the VW stuff and gum things up.
I go out of my way to stick with legit pink G12.
I also decided against that. Read the stuff about clogged heater cores and that was enough to scare me. If it happens again I’ll go grab some g12.
 

CanadianALH

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I have to go there anyway in the next couple days I’ll pick some up likely. It’s weird my coolant is pretty full but maybe not enough
 

irvingj

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Nov 28, 2006
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Etna,NH
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2005 Jetta Wagon TDI (PD/BEW)
My '05 BEW would do that on cold mornings. Shut it down after a few minutes, re-start, no more coolant light. I finally added a bit more coolant, to get the level slightly above the "FULL" mark. No problems since....
 

dieseldonato

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Us
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2001 jetta
On the off chance it's not just low coolant. The sensor pins can come loose amd let them move around, it will give an intermittent issue. That's ultimately what happened to mine a while back. Just ended up replacing thr ball and went in with life..
 

Genesis

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Sevier County TN
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The pins get "stuff" on them over time. You can use a toothbrush on them and it will help for a while, but it comes back. This assumes it not actually low (if it is then the problem is obvious) and since all things expand as they warm up once the coolant warms up a bit it goes up a bit in level. In addition all chemical reactions (including conductivity) are less at lower temperatures. Add the two and if the pins are a bit gunky it will go off when cold and not once warmed up a bit.

Blinking red light and beep-beep on a cold start is a good indication the probe tips are either dirty or you're a bit low on coolant. Since it should never leak if its low more than once (e.g. you did a change with a belt in the summer, now its winter) its leaking somewhere, but if its a once it can be as simple as you did the belt in the summer, you filled to the midline and now when REALLY cold its off the bottom of the pins thus the alarm, and once you run it for a few minutes and turn it off the level is a bit higher and no alarm.
 

CanadianALH

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The pins get "stuff" on them over time. You can use a toothbrush on them and it will help for a while, but it comes back. This assumes it not actually low (if it is then the problem is obvious) and since all things expand as they warm up once the coolant warms up a bit it goes up a bit in level. In addition all chemical reactions (including conductivity) are less at lower temperatures. Add the two and if the pins are a bit gunky it will go off when cold and not once warmed up a bit.

Blinking red light and beep-beep on a cold start is a good indication the probe tips are either dirty or you're a bit low on coolant. Since it should never leak if its low more than once (e.g. you did a change with a belt in the summer, now its winter) its leaking somewhere, but if its a once it can be as simple as you did the belt in the summer, you filled to the midline and now when REALLY cold its off the bottom of the pins thus the alarm, and once you run it for a few minutes and turn it off the level is a bit higher and no alarm.
Belt was done at least a year or so ago PO did it. I have the paperwork I’ll check.
 
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