people have got this replaced under warranty thought right?

 

Yes, but be prepared for the dealer to do a million other things that don't need to be done before they figure it out.
Expect them to replace your radiator, your coolant temp sensor, your hoses, your thermostat and then everything else they break while they are replacing those items - including, but not limited to, your power steering rack, your battery tray, your intake and MAF sensor and, ultimately, your entire engine.

I am NOT joking.

 

that is something to consider then.. hmmm....

 

well, after a long period of getting used to the low coolant light at RPMs over 2500..... i finally bought the scangauge, and i am going right now to unplug the sensor

 

Just wanted to add a ME TOO! to the thread

I've had the car for years, but the light only started coming on a few months ago. It happens nearly every time I first start the car, and stays on for about 15 seconds, then goes out.

And very rarely... I mean like maybe once every few weeks... it'll pop on in the middle of just commuting kinda driving, then go off after 30 seconds or so.

The levels looked OK, but maybe I'll add a little like people suggested...

 

Count me in.......... except prior to this happening.. It's been smelling like pancake syrup.. it's the only way I can describe it... My car is not over-heating and of course the "stealership" had it running for 30 minutes with the A/C full blast...and they still couldn't figure out what was wrong... Go figure!

 

+1

 

you say that as if it's a bad thing - mmmmmmm paaaancakes !!!!

 

^^ I like pancakes too.... but not from under my hood.... lol

Has this happen to anyone else???

 

the mechanic tried to clean the sensor for me last year,but it doesn't work.. just buy and change the whole tank,no more light

 

Pictured is the sensor; could someone that understands electronics a little bit better than me confirm that this is how it works:

this sensor sits inside a spindle shaped tunnel that is molded inside the tank. Around that spindle is a doughnut shaped flotation device that travels up and down this spindle as the water level rises and falls.

I'm assuming that the flotation device has a magnet inside it that lets the sensor know where it is?

 

the string/rope is just for scaling yeah?

anyway, i'm trying to get a look at that and it looks like there are two contact plates meant to close the circuit in the middle? i cant see it really well

I'm by no means experienced with this kind of thing but it seems to me your assesment makes sense. doughnut drops, magnet inside causes the circuit to close illuminating the lamp?

 

No thats a shroud around another thin piece of zinc wire running parallel to the enclosed glass for the second cable coming out of the wiring harness.

If we're assuming that the magnet closes the circuit causing the light to illuminate, then its clear why all the symptoms occur in the order in the way they do.
(i.e. dependent on the rpm load and the temperature there will be a different level of fluid in the tank.)

It could also be assumed that the sensor fails after being magnetized for too long the two ends inside the glass tube naturally become closer together, causing the sensors sensitivity to go way up.

I'm pretty sure that over filling the tank will solve this problem until enough excess fluid drains out of the overflow at which point it returns close enough to trigger this very sensitive circuit.

EDIT: would like to find a fix as if they are just replacing the tank with the same tank, the problem is bound to show up again after 3 or 4 more years, (once most of us are out of warranty).

 

Ah i see.

that does make sense

also makes sense, but even though this was my first thought, actually hearing it makes me second guess it. although OE manufacturers arent always concerned with longevity, i find it hard to believe that this could be the designed function as anyone with common sense would see this being a consistent problem.

perhaps someone else whose had this thing apart can shed more light on this

 

meh?

 

how do you drain the cooling system though?

 

do a search plenty of threads on changing your coolant. If your refering to how i got the fill/overflow tank out without spilling fluid, I used a hand pump (the kind they sell for filling diffs and transmissions to take out the excess fluid in the tank to check out the sensor).

 

I wouldn't be so quick to disconnect the sensor; I cracked my radiator today, and didn't think I should be worried about the light until my car started to may a hot tea kettle noise and my temps were way high up there.

 

How did u crack ur rad ?

 

I'm not sure yet. I know the crack is behind the honeycomb, in a 4x4 section. I'll have a new radiator hopefully by tomorrow so I plan on checking it out.

 

You sure you cracked your rad and its not just coolant purge getting on it? I thought I had cracked my rad to when I overheated firstly.. all the coolant that purged went straight onto my rad and seeped down..

 

i just read this in another thread... sucks to hear.

disconnecting the sensor isnt a good solution for everyone, but it can be for some.

the OEM temp gauge is practically useless, and the coolant light has its own troubles. so for those that choose to disconnect it, it would be wise to look at your coolant everytime your under the hood for oil or whatever, and very wise to be able to monitor coolant temps via scangauge or other gauge

 

Add another 8 owner to the pile.

 

my buddy's 8 started doing this Sunday as we were bedding the brake pads. I think he's out of his warranty

 

it starts off with the light on occasionally , becomming more frequent over time then one day it just stays on -