Abstract: An electronic detection system monitoring coolant level and/or temperature of an internal combustion engine. A unit installed within the cab of a vehicle provides visual and audible warning if engine temperature rises above its normal hottest operating temperature and/or when coolant level drops below a selected level in the coolant reserve tank thereby preventing damage caused by overheating. The overheat detection system may comprise a heat sensor within a bolt which may be screwed directly into the engine head. An additional heat sensor positioned in the bottom radiator hose can be used in series with the engine head sensor. Associated circuitry is adjustable when installed to provide alarm activation when the temperature is a few degrees above the hottest normal engine operating temperature. If the engine starts to overheat, an LED lights up and an audible alarm sounds.