CM2000 Series meter's front display shows an alarm code "991" and user may not know what that means and how to fix it.
CM2000, CM2050, CM2150, CM2250, CM2350, CM2450
Alarm code, Error Message, Power meter retrofit and replacement
If the front display of a Circuit Monitor 2000 displays a 991 message, this indicates an internal memory failure.
It is possible that re-loading the latest firmware for the meter could
correct the issue. If a firmware refresh does not correct the error, the unit will need to be replaced.
The latest firmware for a CM2000 Series meter can be found in FA221408
for information on how to upgrade the CM2000 firmware and for a link to the firmware download utility, DLF-3000.