service engine soon light on 2003 Ford Escort

i noticed my service engine light came on and when i went to get my oil changed and asked them to reset the light they told me that there was a P0125 error, how much does this normally cost to repair?

Asked by for the 2003 Ford Escort
The Service engine soon light/check engine light is not to be confused with a maintenance light . If the Check Engine light/Service Engine Soon light illuminates while you are driving, the car's on board computer sees a fault in the engines management system that is causing an excess amount of pollutants to be emitted from your car. This could result in engine damage if left neglected. Some problems that can cause the Check Engine light to stay on may take two "drive cycles' to complete before illuminating the Check Engine Light. The computer sees a problem and looks for an identical set of circumstances to occur to confirm that it has indeed seen a problem before turning on the light. A Check Engine light that continually flashes while you are driving is serious and is a sign that the computer sees a problem that seriously risks damaging the catalytic converter which may result in an expensive repair or even may cause a fire! Diagnostic codes are stored in the vehicle's computer and can be retrieved using a scan tool that communicates with the computer in your car. We have in our Repairpal website an encyclopedia with in depth articles about computer, and computer control systems, emission and driveability problems.
P0125 is usually a stuck open thermostat about $125 to fix parts and labor.
I have a 2002 zx2 escort with a service engine light on.. Error code P0125.. Replaced the engine coolant sensor and the thermostat twice but the service engine light stays on.. ? Are there any other components I could change in the loop that might be the problem.. IAT ?