These sensors & switches monitor temperatures. If faulty they either send signals to the machines electrical “Brain” which can activates a warning light, shuts down that part of system, or shut down the entire engine all together. Usually these are located in the cylinder block, oil cooler, or in the cooling system. Switches are set up per specific temperatures. Some turn on at a specific temp and some turn off when the area being monitored by the switch reaches that temperature. At that point the “brain” will activate or deactivate another device such as a fan. In the chart below we note whether the part the switch or sensor turns on or off at the noted temperature. The noted resistance measurements can be used for testing/checking for a properly working part. Direct OEM Replacement