Can be either one, but it is most commonly the ECT. You do need to test it as I said Pat. If the thermostat is weak or staying open constantly, it can do this as well. Remove the tstat, boils in water with a thermometer, dont allow the tsat to rest on the bottom, when it opens, take note of the water temp, if it's at the rated temp 195, then it good. If it opens earlier, it's not, or use a hand heal infrared themometer aimed at the thermostat housing, does the engine ever get to 224? The thermostat couldnt have been too much money, if you already have it, install it, and see if the light goes out after it warms up. Book calls for testing the sensors, but temp is temp!
Wednesday, February 3rd, 2010 AT 7:12 PM