Low Coolant Light On but Plenty of Coolant

My low coolant light comes on after about 20 minutes of driving. The temperature gauge is only in the middle of the range. The reservoir is at the correct level when cold (cold fill level). When the light comes on, I check the coolant level and it's just a little higher than when cold. Low coolant level isn't the issue - what's causing this light to come on? Water pump maybe? Anybody else have this problem???

Yes, I have the same exact problem, but mine comes on after 5 min of driving. I have been looking for info on the web but have not found the problem yet?

At least I'm not the only one...

I had a shop look at it and couldn't find anything wrong - they think it's a sensor that is malfunctioning.

In an unrelated incident yesterday, one of my coolant pipes ruptured. The metal coolant pipe that runs diagonally upward along the center of the firewall was badly corroded and finally gave way. You may want to take a look at yours to see if it is corroding too.

I had the same problem after I had to replace a ruptured radiator hose.
To fix the problem I had to replace the coolant reservoir, the low coolent sensor is molded into the bottom of the tank.

I had one get contaminated from oil in the coolant. Sometimes you can clean em, sometimes not. Check the circuit too. HTH

I also had this problem a long time ago. Replacing the coolant reservoir is the solution. There is a sensor in the very bottom.

Here's the deal. The floaty thing that measures the coolant level is sensitive to specific gravity of the coolant. Since the weight of water is heavier than the coolant the floaty thing did not float. If you have added too much straight coolant into the tank or the system, you will get the light in the car. I know because I put in a new tank including sensor and filled it up with concentrated antifreeze. I got in the car after the job and the light came on within 10 seconds of turning the key. :banghead: So, I drained the antifreeze from the tank and just added water from the hose in the front yard. Got back in and no light. I think I am going to just use the 50/50 stuff from now on. It is a little more expensive, but I can do without the hassle. Another plus of using the 50/50 is you don't introduce contaminants into your system. I hope this helps.