An anti-fouling device for an internal combustion engine aftertreatment injector includes a member mountable as an interface between an exhaust conduit and the aftertreatment injector. The member has an inlet to receive air from an air source, and is formed with a passageway to guide the received air to at least one outlet to direct the air to a nozzle of the injector. The air flow surrounds the nozzle to prevent or inhibit exhaust gas from the exhaust conduit from contacting the nozzle.