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What does a 991 error code on a Circuit Monitor 2000 (CM2000 / CM2) display mean?

CM2000 Series meter's front display shows an alarm code "991" and user may not know what that means and how to fix it.

Product Line:
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 lateset firmware for a CM2 Series meter can be found here:

The following link conains the DLF-3000 software, to re-load the firmware of CM2000:

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