The paper shows that stator intermittent ground fault (IGF) events in high-impedance grounded (HIG) generators cannot always be dependably detected using the conventional and some new proposed IEEE protection schemes. Hence, a subharmonic current differential scheme is presented for reliable detection of IGF events. The key advantage of the new scheme is that it uses already available neutral grounding current signal in the existing subharmonic injection protection circuit of HIG generators and as a result it does not require any additional current transformers or hardware. The performance of the proposed scheme is evaluated using simulations with field captured data from a 618 MVA generator.