Low coolant light

On Sunday I'm driving to the store my LOW COOLANT light goes on. So I buy some coolant. I get home let the car cool off and check my radiator, it is full. My coolant recovery tank is also at the proper level.

Been three days already checked levels again and I'm not losing any coolant.

What the car is NOT doing:

1. Not losing fluid
2. Not running hot

I'm thinking coolant level sensor?

My wife's 95 lumina did the same thing several years ago. The sensor is kinda pricey, so I just unplugged the sensor at the radiator. It's on the passenger side of the radiator facing the fender well. It has a clip that slides off to one side for removal. Kinda tight to get to, but can be done with patience.

Not sure where the sensor is....could be in reservoir or in radiator as Gacowboy30 said.....one thing though, if you replace the sensor, if that coolant has been in there a long time, or is contaminated, it will foul that sensor in a short time.....

You can check the circuit just by disconnecting the sensor...light should go out....if it doesn't, it's not the sensor.....the harness is shorted somewhere or there is a cluster problem....

I just experimented with a defective low coolant sensor. I have a spare from a rad I got from a neighbor parting out his lumina.

It appears that these go bad because antifreeze leaks past the seal where the sensor is exposed to the antifreeze.

Wired up like in the car:
12V -> bulb -> black/yellow
ground -> black

Defective sensor is usually switched on when powered up (it uses a 12v feed coming from the dash bulb). Or it will flicker.

I sat the sensor on top of a candle to heat and dry it out. Left overnight.

Checked sensor this morning and it was OFF when dry

Grounded the sensor and it turned on in a couple of seconds. Turned off a second after I removed the ground.

Put sensor in salt solution and put ground wire in the water. Same effect as directly grounding it.

My opinion... the seal will eventually leak and short out the circuit inside... so don't bother replacing it unless you want to do it once the seal breaks.

EDIT: See autozone's coolant level sensor is LIMITED LIFETIME.... thinking I will go pick it up and scan the receipt for when it goes out.

Thanks for the replies! :)

Looks like it turned out to be air pocket, bled some coolant...

Been about a week already and the light hasn't come back on... :)