My wife's coolant light keeps coming on, and when it does the temperature rises about 30-40 degrees. It doesn't do it all the time. I've checked the coolant a few times and it's full. It's got a new 160 degree thermostat. Any clues?

 

The coolant level sensor is bad/corroded. Its on the radiator, near the battery. Little square sensor about 2inx2inch, and pretty flat. You can pull the old one out and try cleaning the prong sensor, or just buy a new one.

 

You said it has a new thermostat in it. Did you bleed the system after installing the new thermostat?

 

Yes I bled the system. I'll check the sensor though, thanks man.