An intake air temperature (IAT) sensor diagnostic module comprises a measured noise module, an expected noise module, an excess noise module, and an IAT fault detection module. The measured noise module measures noise in an IAT signal from an IAT sensor in a vehicle. The expected noise module determines expected noise based upon the IAT signal. The excess noise module determines an excess noise value based upon the measured noise and the expected noise. The IAT fault detection module diagnoses faults in the IAT sensor based upon a comparison of the excess noise value and a first predetermined value.