Coolant Problem

[DanMan68]

My coolant had been low for a while but it was not getting any lower, and I could still see the level in the expansion tank, so I was not too worried about it. I finally decided however, to top it off. I carefully filled it to the correct level, however after about an hour of driving the coolant light came on again. Sure enough the level was right back to where it had been before I filled it up.

Any ideas on what caused this?

[jlevie]

You could have a leak, or an air bubble in the cooling system from the engine running low on coolant that is working out now that there is sufficient coolant. Add more and see what happens.