Coolant Light on Check Panel

[Gavla]

My coolant light light on my check panel went on. I checked the coolant and topped it up a bit.

However the light still keeps coming on. Does this indicate a bigger problem?

Thanks

[AlpineCab]

the cheeky answer is that it depends on whether you are actually losing water or not.

When the light comes on, whats the level of the water? are you always having to top up each time the light comes on?

[capri_rob]

The sender units are fragile and can break which puts the light on - about £10 from ECP to replace

[Rtaylor2208]

+1 on the failing. They can also get pretty gunged up, take it out and give it a good clean and make sure the float part moves easily, this worked for me for a whole before it gave up the ghost and I had to replace it.

[Gavla]

Thanks gents, I am not losing coolant so will check the sender unit.

[Brianmoooore]

You won't see anything visibly wrong with the sensor. The problem is that coolant eventually gets inside the stem and rots the very fine wires to the reed switch that's in there. The two pins on the sensor should be short circuited when the level is correct, and open circuit when the bottle is empty.
If and when you buy a replacement, compare its length with the original before you fit it. The majority of level senders sold by the likes of GSF or ECP are the type that fit in the underside of a coolant tank, and I've had more than one occurrence of them supplying the wrong one, which is of a slightly different length.
Rtaylor2208 - if your sensor is 'gunged up', then a non working level sensor is the least of your problems!

[Gavla]

Thank you Brian!

[Rtaylor2208]

Brian it was a strange one, the coolant was clean with no signs of contamination but inside the plastic of the sensor case was gunged up. Other than that no signs of any coolant issues. I put it down to it being 22 years old. Since changing it about 1K ago it's still clean as a whistle.

[polsta]

a problem i have got, my coolant sensor light has always been on since ive had the car, something with the wiring somewhere i think, i replaced the sensor with a brand new ECP one and it was still the same, although not had the car here to really get to the bottom of it

1st thing i will be checking when i can, is to put the 2 sensor wires together to see if it turns off the light

if not, what would be the next things to check ?

[Gavla]

Ok, so had a look at the coolant sender unit, seems fine? If I push the float up the light goes off. float seems to move freely but when I put it back in the coolant the light is on.

Guess it is worth replacing.