Cessna Skyhawk 172N Pilot Operating Handbook page 200

Figure 2-1 AED/CED
Note:
Page 2-6
Issue 2
Revision 7, Jan. 2018
Reims/Cessna (F) 172 N&P
The AED/CED caution lamp is switched on
if an engine reading is in the amber or red
range.
The AED/CED caution lamp remains on
even when the parameter returns to the
green/normal operating range and must be
confirmed by pressing the Confirm/Test
knob.
After being confirmed, the AED/CED cau-
tion lamp will switch on again whenever
another parameter enters amber/red range.
Pressing the Confirm/Test knob longer than
one second will initiate the power-up test
sequence.
Supplement POH
with TAE 125-02-114