You will have to remove the gas tank and install a fuel control module. Before you do you need to have someone check for power and especially the ground for the fuel gauge.
get a new temperature sensor.
The most common reason for the fuel gauge in an Impala to stop at half full is a bad fuel sensor. The sensor is mounted inside of the fuel tank.
It is easier and cheaper to replace the temperature sensor--try that first
# 1 check point..Your sending unit has worn out. No big deal...Easy to replace..
Replace your thermostat had same problem it sets a code but no check engine light
The fuel gauge sensor is located in the fuel tank. The fuel gauge sensor and fuel pump are one assembly. To my knowledge they are sold as one unit and is fairly expensive. The fuel tank must be dropped to R&R the assembly.
If the vehicle will stall and will not restart or appears to be out of fuel but the fuel gauge reads above empty, replace the fuel sensor assembly and auxiliary tank fuel level sensor if equipped. if not, replace the instrument cluster.
my o6 chevy impala is lighting up on the dash that the engine is hot but the gauge is saying its cold what is wrong and how can i fix it?
The temperature sensor is bad or a pinched wire. I don't know Impala specifically, but most newer cars have two sensors, one for the cooling fan and one for the gauge. The sensor provides the ground for the gauge and if it shorts out that causes it to be fully ground. If you unplug the wire on one sensor and it still goes to hot, that sensor is for the fan. Without the wire connected the gauge shouldn't work. I'm assuming it is just the gauge reading hot but the engine is not? Goes to hot as soon as you turn the car on?
get a circuit tester and start looking with the key on
You need to replace the gauge cluster... I hate to say that, but that is the only fix. It is common on the silverado series trucks as well. This was verified by 2 mechanics and the Chevy dealer.
I have an 05 impala and had problems with the speedometer and fuel gauge. The only way to fix it was to replace the whole instrument cluster. Pretty easy to do, only took about 45 minutes.