Abstract: A flow hood assembly for an engine aftertreatment system having a particulate filter and a selective catalytic reduction device is disclosed. An outer case defines a cavity, the outer case having an inlet and an outlet formed therein, and a neck section formed between the inlet and the outlet. A socket in the outer case is in an opposed relationship to the outlet and is shaped to receive an injector that introduces a reducing agent into the flow of exhaust gases. A baffle reduces a cross-sectional area of the cavity at the neck section to increase exhaust gas velocity at a sensor positioned at the neck section. A deflector member in the cavity between the baffle and the socket directs a portion of the exhaust gases towards the socket and across the injector nozzle.