Thats a reed switch, I know that much. I'd think that it would be operated by a magnet inside the float, but i can't say I've ever examined the tank.

So is it the float thats failing? or is it the switch itself is the real question.

It started with maybe twice a month. Now it's 3 times a week. If it gets worse, I'll unplug it. Melt the damn car to the ground. I don't care anymore.

Just got my car back from the dealer. They changed the coolant tank & sensor. No light now.:)

ill try to take out the tank and shake the bejesus out of it.
my light comes on with some spirited driving (flooring it) and goes away as soon
as the RPM's drop.

mine came on once when i was at the track at 9.5k rpm's lol....but i was a tad low on coolant

Thats how mine started. The light went off after slowing but then slowly started coming on more and more in the next few months.

For those of you who had the tank replaced by the dealer and were under warranty. What was the out of pocket expense, if any?

100% Warranty!:)

Odd, my light has been on twice. Both times it was while driving in snow. Came on for a couple minutes then went off.

Mine does this when I'm driving spiritedly, but in those instances the level is always good. I check all my fluid levels constantly.

Funny enough this past week I was flushing out my coolant again (third time in four weeks; long story) and I guess the air was burped out. When I was driving around I heard a bunch of air gurgling noises in the heater core. I ended up driving back and checking the level; I think the overfill tank was so low that air was actually being sucked in coolant flow and that was what the noise was. Topped off the level and the noise disappeared. The light didn't come on at all so now I officially think the coolant light is useless.

This week my 1 time coolant sensor glitch became consistent. Extended high RPM driving (6.5K rpm and up) causes the coolant light to come on. Slow down and it turns back off again. May have to visit the dealer if it keeps up.

Update:

So I went and actually checked my coolant level today. turns out it's low. Is it normal to loose enough coolant to go from "F" to "L" on the overflow bottle over 6 months of daily driving?

Hi to everyone. I got the same problem. A change of the coolant reservoir will solve it. It has a sensor located inside the tank so no chance to just reapir the sensor. The part cost around $150. If DIY, watch out with the short "hard to reach" L hose. You ca easily break the the small conector on the radiator cover (unfortunatelly happened to me). To change, need to take out battery/bat box and air intake box.

i had mine replaced about a year ago and all was well.........
until about a week ago my light started to come back on while driving my car pretty hard, now it comes on for almost normal driving. checked the coolant level and it was ok and i even added some more but no dice. im out of warranty now so theres no way im going to pay the 400 for a new bottle. im just going to unplug the connector that mm mentioned. any others that continue to have the same problem after having the bottle replaced?

My coolant sensor went bad too, after 5+ years and being out of warranty :( #$%^&.

So, of course I'm ignoring the low coolant warning light because I know the sensor is bad.

Then my water pump or water pump gasket went bad @57k miles ......... I find out while driving home from work at night when I started smelling burning coolant and see steam coming from under the hood.

My recommendation is that if you don't have a real temperature guage (stock crap guage does not count) get the coolant overflow tank replaced ASAP, otherwise you're asking for trouble by disconnecting or ignoring it. You can buy one for less than $200. Cheaper than cooking the engine.

I replaced the water pump, thermostat, and coolant overflow tank. All is well so far :).

DAMN it, mine has started! Comes on ocassionally when I FIRST start the car, usually turns off in less then 30 seconds.
I've seen it 3 times in a week. :banghead:

that is not how it works. you are just a bit low on coolant. :)

this happens when the car is warm..

beers :beer:

you know Swoope, you might be right!! Easy_E1 removed the engine hook from my car and a bunch of coolant came out from the water pump, that probably did it...

thanks

ha! Jedi you n00b!

According to MM's post earlier, it might not be as serious as it seems...

hopefully :fingersx:

+1 to the list

This post has been a good read.
I keep getting the coolant light on mine.
Garage want to replace the whole thing as the sensor bust. £226!!!!
And even tho i got extended warrenty they say its not covered. Hmmmmm

Add mine to the list.

Mine usually comes on during longer trips say interstate at 80mph approx for an hr or longer. It will come on for a short time then go away. I've seen it pop on several times. Every time it's come on so far I've stopped and let cool for about and hr or lately I've even waited till the following morning before I go to work I check it. Level is fine. Not to worried about it. I also keep a close eye on engine temp just in case. If it is so unreliable as several have mentioned I'll look into an alternate means of monitoring engine temp.

Mine has been doing this for the better part of a year. I check the coolant often enought to know it rarely is b/c the level is actually low. The first few times this happened I kept checking the level and giving a head shake and a WFT? (thanks for yet another dummy guage :uhh:)

My concern ATM is the increase in frequency over the last week or two. I have no problems with the 8, but I did notice about 2 weeks ago what sounded like a slight change in pitch to the engine noise. It seems to me the normal whirring noise at idle is a slightly higher pitch. Could this be my water pump working a little harder and working on croaking? And would that have any impact on the coolant light increasing in frequency/duration?

Thanks.

Change the coolant reservoir. Mine began appearing at high speeds, then everytime no matter how fast or slow you drive. My 8 is 2004. In my case, I ended up changing the coolant reservoir. It has a sensor inside, at one of its side, that there is no chance to change it so you have to change the reservoir. Should be between $150 to $200. If DIY, watch out with a short hose the reservoir has at the back (called the overflow hose) since it is very easy to brake its conection to the plastic radiator cover.

ok,

if you are going to replace the tank, try this first. i have done this with three different types of cars and it has worked..

take the hose you wash the car with. spray nozzle on full. and put it in the reservoir and turn it on.

it dislodges a bunch of crap in the tank.. and usually the stuff around the sensor.

and well if it does not work you are going to buy a new tank anyway..

btw, my tank is on 107k miles. :)

beers :beer:

Were these cars exhibiting "low coolant light" syndrome with coolant level fine? What type of cars?