How will the EGR valve be controlled if it isn't connected to the ECU? That is assuming that the JDM ECU has the controller logic installed/switched on for the EGR valve in the first place...
I think you need to go back to the beginning. The EGR is a red herring.
Are you sure you're talking about CO2?
If you're talking about CO, which I suspect you are, then what limit did it fail, at what lambda etc.? What limit did it have to meet? What were the HCs like?