Diagnostic interrupt and Hardware interrupt have no bearing on the actual readings themselves.

From what I understand, you are using 6 of the 8 channels. Of these 6 channels, 4 are reading ok but 2 are reading over range. Is that right?

You should check your front connector wiring. Since the behavior is identical after replacing the module, the problem is more likely with front connector wiring.

Also, try after deactivating the unused channels in the HW Config.

All the best