Alert! Air temperature sensor not detected. - Dell Optiplex 745

Dell fans typically have a sensor built into them. So it sounds like that sensor may have failed.

A number of vendors sell Dell OEM parts, so check around on the net for the fan. If you can't find one, call Dell Spare Parts.

Note: If you replace the fan with a non-Dell fan, you'll still get a fan failure error at every boot.  And keep an eye on it to make sure it doesn't overheat.

Ron

Thanks Ron!

The fan with the sensor is the large one near the CPU right? It forces air over the massive heat sync on top of the CPU. The fan itself is still working... so I wonder if it is worth it to get a non-dell one... as I would be in the same situation, wouldn't I? I mean a working fan with no temp sensor.

Cheers,

Tyler

Yes, a non-Dell fan leaves you with the same error message situation.

But the real issue is heat. I don't know how this model handles the fan if the sensor fails. Without the sensor, the fan either may run continuously at full speed (probably not a problem, except perhaps for noise), or it may not speed up when things get hot.

You might want to disconnect the fan cable from the motherboard and then reconnect it, in case it's just a loose connection. Always power off, unplug and press/hold power button on tower for ~15 sec before working inside the case.

If you're still under warranty, contact Dell Tech Support for a replacement fan. If not under warranty, you'll have to decide whether to live with the error message or get a replacement Dell fan.

Ron

Hi, I have the exact same issue (Alert! Air temperature sensor not detected), it came up just after this weekend, when I cleaned the inside of my pc.

Have tried to unplug/replug the fan, reset, power off, etc etc. but the error keeps getting up when rebooted.

I guess the only thing that will solve this is placing a new (original) Dell fan (with temperature sensor) in the machine.

How to I obtain a new (used but still working is also OK) Dell fan for my machine? I have a Dell Optiplex 755

Please send tips or helpfull information to my email address: <ADMIN NOTE: Email id removed per privacy policy>

Thanks

Mathijs Groen

The air temperature sensor that Dell installs on systems works without any user interaction. There is no need to turn it on or off or to configure any settings. The sensor comes configured for optimal running configurations no matter what climate you use your computer in.

However, if the desktop halts with an “Alert! Air Temperature sensor not detected” Message During Startup, one of the solutions is to "Reseat the Thermal Diode Power Cable" or Check the cable and connector in the Power/USB Front Card.

Please click on the link below for steps to reseat the Thermal Diode Power Cable. Read the Safety Information in the same link prior to opening the system chassis. Dis-assemble the system chassis only if you are comfortable doing so.

http://dell.to/13522yd

Rebtek - This thread is more than 3 years old... :emotion-5:

The sensor is a part on the front panel board or attached to that board via a cable. The cable goes to a black plastic sensor that locks into the case where the air comes thru.

i replaced the fan but not working......