I live in a second floor apartment and have been struggling to find the cause of a sewer smell in the bathroom since I moved in. The waste pipe doesn't have an external vent but has a AAV on the top of the stack on the 4th floor. When the AAV is removed from the stack the issue is resolved in my apartment. All of the drains have been jetvac'd recently and I've been assured they're clear. No one else connected to the soil stack is complaining of an issue. Does this mean that there is potentially a gap in my own soil pipe (there is no leakage or water collecting anywhere) for the smell to vent when the valve is replaced? My soil pipe is routed behind tiles etc so before removing them to investigate further (big job) I'd like to know where similar issues have been pinpointed before... Thanks in advance.