Maintenance and Service Guide
Control panel message Description Recommended action
90B-Fan Failure The system has detected that a cooling fan is 
not operating correctly.
1. Reseat fan.
2. Reseat fan cable.
3. Replace fan.
90D-System Temperature Thermal shutdown occurred. The system BIOS 
has detected your machine was previously shut 
down to avoid overheating. Overheating may 
occur if the cooling vents are blocked or the 
operating temperature exceeds the system 
specications. The machine should return to 
normal operation once the situation is resolved.
Make sure system has proper airow.
90E-Power Supply Fan Not detected Power supply fan is not connected or may have 
malfunctioned.
1. Reseat power supply fan.
2. Reseat fan cable.
3. Replace power supply fan.
910–Filter Warning Airow lter is dirty. Replace the airow lter.
Interpreting system validation diagnostic front panel LEDs and 
audible codes
During the system validation phase that occurs at system startup, the BIOS validates the functionality of the 
following subsystems and conditions:
●
AC adapter
●
System board power
●
Processor failure
●
BIOS corruption
●
Memory failure
●
Graphics failure
●
System board failure
●
BIOS authentication failure
If an error is detected, specic patterns of long and short blinks, accompanied by long and short beeps (where 
applicable) are used to identify the error. These patterns will make up a two part code:
●
Major – the category of the error
●
Minor – the specic error within the category
NOTE: Single beep/blink codes are not used.
Number of long beeps/blinks Error category
1 Not used
2 BIOS
3 Hardware
Interpreting system validation diagnostic front panel LEDs and audible codes 89










