2007 pacifica the engine light came and the gas gage want from 3/4 full to empty

2007 model year car has on board diagnostics level 2 (OBD2), a scan tool is required to retrieve codes stored in the computer in your car. The computer needs to look at fuel tank fuel level when doing an evaporative emissions leak test, if the fuel tank sender unit has failed the fuel gauge will not read and the Check Engine Light will come on. Before condemning any part as being bad proper diagnostic tests need to be done.