replace fan with resistor
If the fault detection depends on current variation with rotation, the resistor isn't going to fool it at all. After all, current will not drop if the fan stalls with dog hair, but air flow will, so simply detecting the current is about useless for detecting fan failure (and is seldom used). Tachometer fans have an extra lead for this purpose, but it can be achieved without extra bits. 

You could probably make an oscillator circuit to fool it that would be close enough, but it might be easier to search out the controller and disable it or just replace the fan with a quiet one. 

For an example of a current detecting controller, the Microchip TC64x series uses a current sense resistor on the low side: 



I would suggest replacing the fan.. the rule of thumb is every ten degrees C of heating halves the life of the product.