Sending units keep drivers apprised of import fluid and temperature levels in their Jeep Wranglers. The three most important sending units are the temperature sending unit, the oil pressure sending unit, and the fuel sending unit. Without them drivers would not know how much gas or oil they had in their cars or when their engines were running too hot. These devices are generally pretty reliable, but if they do go bad they can cause a whole host of problems. If you suspect that the gauges on your dash are inaccurate, it is important to have the corresponding sending units tested as soon as possible.