Temperature sensors and thermostat on 2005 -intermittent check engine light

check your coolant level in the radiator.. you might be getting the check engine if its low.. also you might have moisture getting into the connector on the sensor when the weather changes.. when the light comes on try wiggling the wires and see if it goes out, could be a loose connection... its a 13 yr old car so the gremlins can be anywhere .post the error code if you can maybe someone can help that way... happy hunting

 

$1700 for temperature sensors? That's ridiculous. You may have being swindled.

Does your radiator fans come on, for instance when the engine is hot, that it needs cooling? If it does, automatically, your temperature sensor(which is called coolant temperature sensor) is functional. You only have one temperature sensor on that engine, and not two, since its not a V engine configuration like Nissan that has got two temperature sensors.

Thermostat is a different component altogether. Its mounted on the side of the cylinder head, where the upper radiator goose hose connects. It might be stucked closed or so. Are you experiencing any overheating issues or what.

Buy a scantool and get the car scanned yourself.

 

Was the diagnosis originally from a Toyota dealer's workshop, or just some non Prius mechanic?