The temperature sensor is located near the front fan on each of the four chassis. The locations are as follows:Sensor Location Signal Cable Mini-tower Integrated into the front I/O panel Shared with the I/O ribbon cable Desktop Integrated into the front I/O panel Shared with the I/O ribbon cable Small Form Factor Snapped into the front grill of the chassis in front of the fan 2-wire signal cable connects to the I/O board (shown below) Ultra Small Form Factor Integrated into the system board No cable necessary
The image to the below shows the air temperature sensor on the SFF chassis. The 2-wire cable runs across the bottom of the chassis and connects to the I/O panel.
If the cable from the control panel to the system board is disconnected, the system displays an error on boot:
Alert! Air temperature sensor not detected
This message indicates the system did not detect the presence of the sensor or the cable is disconnected. Reseat the cable and reboot to see if the message still appears.
If the temperature of the sensor rises above 42° C (107.6° F), the system logs an error (Air Temperature Out of Range) in the Event Log accessible through System Setup. The air entering the customer’s system has exceeded the 42° C standard, and the system must now compensate with increased fan activity and noise.NOTE:
i have optiplex745sff with intel core to duo processor e4400 2.0gege hz
at the start up error msg appear
1. Alert rare fan failure
press F1 to continue or F2 to run setup utality
plz any one help me to fix this problem
my mailing id is
The Rear Fan is under the hard drive in the sff.
release tabs (2)
hard drive bracket
DELL Hard Drive Blower Fan Plus Hard Drive Bracket and
Fan Caddy for OptiPlex 760 / 740 / 745 / 755 SFF & Dimension 5200c SFF
Dell Part Numbers: NY290, TJ160, NH645, NJ793
I too get this warning:
1. Alert rare fan failure
press F1 to continue or F2 to run setup utility
I moved the HD and turned the computer on, and the fan is running fine. The error seems to intermittent, but I want to figure out what is causing it. What other troubleshooting steps should i take?
i have the same problem with the rear fan
i have dell optiplex 745, i bought it today and it shows the msg
which states rear fan failure
i opened the case and found that there is no rear fan in my computer
i dont think i will be able find the fan here and buy it .
i just want the msg to be removed
The error usually seems to occur when a dual core processor is added to a 745 SFF with no disk fan present. Dell (the bios) seem to think the system will then have disk which needs a fan. The opposite is true as the dual core gives off less heat than a pentium D. A fix which worked for me was to run the sense wire (yellow in my system and at the at the edge of the 5pin connector) to both front case fan connector and also to the matching pin on the fan connector for the disk fan. The rear fan then looks to be present for the bios. You need a spare dell 5 pin connector to do this, Easy to get by buying an old dell 5 pin fan on ebay. You should check the ebay picture to be sure it is 5 pin fan.