A filler neck assembly including a main channel for supplying a liquid into a tank and an auxiliary channel for evacuating gas from the tank. The main channel includes a tubular main body including a first end receiving a filler spout and a second end discharging the liquid into the tank. The auxiliary channel includes a first section and a second section, the first section being a channel integrally molded with the tubular main body, and the second section being formed by a feature on an exterior of the main body cooperating with a separately formed part.