Casella CEL CEL-296 - Manual (Page 63)

8. ERROR MESSAGES
When the CEL-296/3 is switched ON, it performs a self test
operation lasting for about 10 seconds, during which time the display
first shows "CEL" then "CEL 296".
Should the instrument fail any of these tests, or one of the
continuous check procedures performed during its operation, one of
the following error messages will be displayed.
Message
0
11
12
13
14
15
16
17
18
19
20
21
22
99
If any of these messages appear, switch the instrument OFF then
ON again and restart the measurements.
Should any of the messages persist, return the instrument to the
local Agent or to CEL at Hitchin for service, including a note of the
error message displayed.
CEL Instruments Ltd CEL-296/3 Operator Handbook Page 63