Since the gauge does not read empty, it is not a problem with the signal to the gauge.
To fix this problem, the gauge cluster will need to be replaced.
The rest of the cluster is OK, Replace the entire cluster? I've read online about the steppe motor, could it be that?
How would i test the system to isolate the root cause?
Sorry for the confusion. IPC stands for instrument panel cluster.
PCM stands for powertrain control module-or-engine control computer.
The problem is most likely the stepper motor within the gauge cluster. These are not serviced, even at the dealer level. The entire cluster is normally replaced. There are some companies that rebuild the clusters, several of them sell on ebay. You can get a replacement cluster starting at around $150 on ebay with the correct mileage already programmed in.