Don't know if you have the service manual. It is in the my post about the service manual.
The manual says to check the connectors on the valve, check Fuse 32 in the Battery Junction Box, check the voltage going to the valve, (which is a PWM signal), check the internal resistance of the valve, and if that is all good, then replace the valve.
The valve is Water Valve CV6Z-18495-B
After a quick search the cheapest price is $118 at www.rockauto.com
<- very reputable company
It is a common part for Ford Focus, Motorcraft YG436