I'm having a problem with my low coolant warning going off with a red warning light and the check engine light going on. Whenever i check my level it is ok. Could this be a problem with the sensor?

 

It appears that the low coolant problem has had more to do with the magnetic float inside the reservoir than the actual sensor. The float is a movable ring around a vertical tube that isolates the sensor from the coolant. It can get 'sticky' due to crud built up in old systems. If you can catch the low coolant message with the engine cold try opening the reservoir and stirring the coolant with a plastic spoon or something similiar. If the light goes out it is the float.

If that fails to indicate a float problem the sensor is a separate part easily replaced.

Have you been able to read the code(s) associated with your check engine light?

 

Although the sensor is a replaceable part, if you have a little extra budget available for the repair, and the internal part swap worries you, you can get a whole new expansion tank, with the new sensor in it and a new cap online for $180 or so. I found the hose removal and tank swap less stressful.

 

I did not know if I should start another thread.

test point, xk8florida, and Gus had excellent info about the float inside the coolant reservoir that was stuck.

When the coolant is filled almost to the neck of the reservoir, can you see the float?

Is the float the same as the plastic ring with a magnet in it in Gus' photos?(See DIY Repair thread)

I think mine is stuck, but cannot see it or feel it.