An exhaust gas treatment system for an internal combustion engine is provided. The exhaust gas treatment system includes an electrically heated catalyst (“EHC”) device in fluid communication with an exhaust gas conduit, a generator, a selective catalytic reduction (“SCR”) device, and a control module. The EHC device includes an electric heater and an EHC catalyst that is heated to an EHC light-off temperature. The generator is selectively operable in a target voltage mode to supply a target voltage to the electric heater. The target voltage represents a voltage required by the electric heater in order to maintain the EHC catalyst at a catalyst temperature. The SCR device is in fluid communication with the exhaust gas conduit. The SCR device is located downstream of the EHC device and includes an SCR catalyst that is selectively heated by the EHC device to a SCR light-off temperature.