Get your semi Ready for the Road Ahead with an improved method of monitoring coolant levels, with the Dorman 4.5" Engine Coolant Level Sensor. With a sophisticated design, this replacement device works to observe the level of coolant in an engine, sending diagnostics back to the display panel to alert operators of low levels. Manufactured with a robust design to withstand harsh conditions and a range of temperature variations. FleetPride is your First Click in Heavy Duty .