One year ago I replaced the coolant expansion tank. Several months ago I started getting a coolant level low message. The first time, the coolant level was actually low and so I topped it off. However the message kept coming back. I finally had some time to look into this and fitted a brand new sensor. Sadly the error remains. I've checked the connector and harness and see nothing amiss, and for reference, nothing had been done to either prior to the error message. Anyone have ideas what could be the cause of this annoying message?

 

Sometimes the float in the tank that the sensor is reading gets stuck in the lower position. You can try to remove the tank and shake it around to dislodge, if that’s your problem.

 

Removed the tank and can see the float at the bottom. I can move the float up with a magnet but it sinks immediately. Lasted less than a year, Dorman brand, going OEM now.