An exhaust gas aftertreatment system includes an outlet housing body, an outlet housing fitting, an outlet sampling system, and an outlet sensor. The outlet sampling system includes a sampling bowl and a sampling ring. The sampling bowl is coupled to the outlet housing body and extends away from the outlet housing body so as to define a sampling bowl cavity between the sampling bowl and the outlet housing body. The sampling ring is coupled to the sampling bowl and separated from the outlet housing body by the sampling bowl. The sampling ring is coupled to the outlet housing fitting and defines a sampling ring cavity. The sampling ring includes a plurality of sampling ring inlet apertures and a connector. The sampling ring inlet apertures are each configured to receive exhaust gas from within the outlet housing body and provide the exhaust gas to the sampling ring cavity.