BENDIXKing AeroNav 910 Pilot's Manual page 349

<app>
Function Lost
The <app> application (e.g. Datalink, Lightning Sensor,
Traffic, etc.) monitored by the AeroNav stops reporting a
status message. If the problem persists, contact a local
dealer for service.
CrossSync
Fault

Dual AeroNavs have been installed and configured to
share data between the units, but there is no
communication between the AeroNavs. If both units are
powered on, contact the BendixKing Service Center or a
local dealer for service.
Timer
Expired

The generic countdown timer has expired.
<Custom
Timer>

The <custom timer> has expired. Custom timers can be
created using the Aux-Util page. This message will persist
until the timer has been manually reset.
IFD Fan
Failure
Contact a local dealer for service.
89000039-010
Rev 1 May 2019
AeroNav 900/880 Series Pilot's Guide
<app> function is not responding
Attempting to re-establish CrossSync
Timer Expired
<Custom Timer> Expired
AeroNav Requires Service
General 7-19