My coolant warning light is starting to come on and off intermittently. I have read a lot of posts about this lately so I know it's a common issue and usually means that either the sensor is fubar or there could be some air in the coolant and it needs something as simple as bleeding the radiator.

Considering it only started to come on after I had my water pump replaced, I suspect it's the latter, however I have a few questions which haven't been answered in previous threads about this topic:

If the sensor is in the reserve bottle, then the issue really should have nothing to do with the water pump itself, correct?

If I was to wait til my next service (still 8,000 km away) to have my radiator bled, am I risking anything? Bearing in mind that I check coolant levels religiously and I have never had the need to top up.

I find it concerning that the light does come on after some spirited driving, even though the temp guage does not move at all - is the sensor some how detecting an increase in coolant temperature that the guage isn't showing? Or could it be that I am somehow starving my car of water? Considering the sensor is in the overflow bottle, am I safe so long as there is enough water flowing through the system?

Thanks in advance.

Since you check your coolant level often.............you are okay.............no worries. If you get too hot, then the stupid gauge in the car will pick it up. Mine will set just below halfway and my coolant light is acting up more and more as I get on it. I just ordered one as the sensor is molded into the bottle and you must by the bottle. I watch my level as well, my stupid gauge and my better gauge I have installed and all is fine..........it's just that light bugs me!!!!!

When the car gauge show increase it will be way over 110 degree. So watch out for that... it moves = BACK OFF!

Hmmm... make sure you have the red radiator light not the yellow fountain washer light. I made a mistake years ago and panic for no reason.

No, it's the red light. I read some of your previous comments on this too - I am surprised there is a warning light for washer levels.

It's a faulty sensor if the coolant light goes off and your not low on coolant. The stealerships usually replace it under warranty.

If they do not want to replace it under warranty or you're out of your warranty period then disconnect the coolant light sensor connector located conveniently right next to your coolant reservoir and check the coolant manually. That's what I did with mine. :)

I appreciate all the responses so far but no one has really answered my questions. I know what the problem is, I just want to be assured that there will be no issues if I do not replace the sensor or have my coolant bled (depending on what the issue is).

The car is just out of warranty and I am not keen on removing the sensor. It's there for a reason IMO.

I have learnt to ignore the problem. My red light only comes on when I am on the track.

I have taken the added precaution of adding a second oil cooler and a new radiator cap that can handle higher pressures..this leads to a higher boiling point which means less bubbles.

skc

mazurfer answered your question. you need a new coolant box. there's a tsb for the faulty sensor. they give you a new box free. but you're out of warranty.

you have to replace the whole box on your own.

if there's no or low coolant, having the light and sensor not working right would be bad, i agree.

DrGonzo, the sensor is a sort of magnetic ring that floats up and down a plastic rod. There are 2 things that can go wrong, firstly is that the magnetic ring starts to stick (This happened to me when I ran the coolant level to low. It was exacerbated by air in my coolant system, ie it constantly dried out the plastic rod. I swished some neat coolant around in my bottle for a few minutes before putting back in and it seemed to help until the second problem occurred.

The second problem it the sensor that is inside the plastic rod (reed switch) gives up. SFA you can do about it but replace the bottle.

HTH

Andrew

I am guessing it is not the sensor that is the problem, based only on the fact that the light never came on until the water pump was changed and I don't think it's a coincidence. So, if it is in fact air in the cooling system, will this present a problem further down the track? Should I have my radiator bled as a matter of urgency?

If it is the sensor afterall, I appreciate that the entire bottle will need to be replaced and I appreciate that it will not be overly cheap. I also appreciate that the light coming on in this instance wouldn't be an issue as long as I keep an eye on my coolant levels, which I already do.

Thanks again for the comments.

yup after my last oil change my light started coming on n off and my coolant level is good so im guessing its the sensor and if i were you i would bleed the coolant just to be safe

My light is on permanently. Stealership even told me that l could swap 200 big ones for a new coolant bottle, l told them l can put up with a red light :-D

the only way this will stop is if you change the over flow tank, bad sensor. i have this problem and i gets me so pissed. even topped off my coolent little past F. your 8 is fine till i think 220º but by this time your 8 is already at critical mass. 230º and your F'd. look into a water temp gauge totally worth it. jedi54 has a really good DIY thread on it. well hope i helped.

what if the temperature gauge actually moves? could it also be a faulty sensor? my coolant overspilled in my engine bay and it has been having problems ever since

I say pull the damned plug like most of us have done and be done with it (unless you're still in warranty).

AS J03 has said, if you're really worried about it get a water temperature guage. The OEM coolant level sensor is not something to rely upon.