Maybe a problem with instrument cluster?
The temp gag e defaults to 160 degrees if,
The pcm detects a malfunction in the engine coolant temp sensor circuit.
The ipc/instrument panem cluster detects a loss of class 2 communications with bcm/body control module.
The bcm detects a loss of class 2 communications with pcm/power train control module.
The fuel gage defaults to empty if,
the pcm detects a malfunction in the fuel level sensor circuit.
If ipc losses communications with bcm.
If bcm losses communications with pcm.
Check applicable trouble codes. Some of the national brand autostores will check codes for free. See if the codes will point in correct direction?