Temperature gauge and fuel gauge do not work???

Its possible it could be a fuse but usually if it was a fuse the whole dash would quite working but you can check if i remember correctly the 2004 impalas had the fuse panel either under the driver side dash or in a hide away panel that can only be accessed with the driver side door open which should have a reference image on the cover you remove if its not a fuse its probably a fault somewhere else in the electrical circuit.

Same prob/ Replaced sending units worked(sort-of) for all about 2 start up/shut offs. Must be guages. recommend locating wiring to both fuel and temp sending units buying external(separate) gauges and mount them on dash or roof support