  We present 1/$f$ noise measurements of IrO$_2$ nanowires from 1.7 to 350 K.
Results reveal that the noise magnitude (represented by Hooge parameter
$\gamma$) increases at low temperatures, indicating low-frequency resistance
noise from universal conductance fluctuations. The cause of this noise is
determined to be due to oxygen vacancies in the rutile structure of IrO$_2$.
Additionally, the number density of these mobile defects can be calculated from
the $\sqrt{T}$ resistance rise caused by the orbital two-channel Kondo effect
in the Dirac nodal line metal IrO$_2$.
