Hi Tony,

I am not sure how much help this will be to you but I had a similar experience to yours with a Hyundai a few years ago.
The P035x code seems to be quite rare and from its description you would assume it is set due to an electrical fault but that is not so. With mine I proved it could be set by a misfire even though you would expect that to set a P030x code.
I would suggest you look at compressions, both leak down and pressure as well as scope volts and amps on the secondary.