Cisco Catalyst 4500 series supervisor engines that run Cisco IOS Software sometimes display fan failure error messages in the log files.
Cisco bug ID CSCeg70330 identifies this problem. This is a cosmetic bug, and does not impact the functionality of the switch.
Fan failure messages indicate that the fan-tray failed. This problem can occur in the Cisco Catalyst 4507R or 4510R chassis. These are some log messages from the switch that runs Cisco IOS Software Release 12.2(20) EW or later:
%C4K_IOSMODPORTMAN-6-FANTRAYGOOD: Fan tray is okay
%C4K_IOSMODPORTMAN-4-FANTRAYBAD: Fan tray has failed
%C4K_CHASSIS-2-INSUFFICIENTFANSDETECTED: Too few working fans in fan tray, the chassis will overheat. If not resolved, in 5 minutes all line cards will be placed into Reset-Mode
These messages do not have any impact on the switch performance. The failure recovers within 30 seconds.
The bug is now fixed in the versions 12.2(18)EW03, 12.2(25)EWA, 12.1(26)E01, 12.1(26.1)E, 12.2(25.1)EWA, 12.2(25)EWA02 and enhanced to capture more information to confirm the failure before such messages are logged.