Accu-Chek Performa Owner's Booklet page 66

The temperature is above or below
the proper range for the meter. Refer
to the test strip package insert for
system operating conditions. Move to
an area with the appropriate
conditions, wait 5 minutes, and
repeat the test. Do not artificially
heat or cool the meter.
The battery is almost out of power.
Change the battery now.
64
The time and date settings may be
incorrect. Make sure the time and
date are correct and adjust, if
necessary.
Note:
If you see any other error display, please call
Roche.