When ever the dryer is used I get a sewer smell coming in the bathroom exhaust fan

Only way that would be possible would be if the bath exhaust fan is not properly vented to the outside.

Only way that would be possible would be if the bath exhaust fan is not properly vented to the outside.

Thanks I think they hooked the bathroom exhaust vent into the vent stack pipe in the attic, will have to crawl up there and check to be sure.

If they did hook it up to the vent stack - then it is very wrong. Disconnect it, plug the hole, and reroute it.

Milo

Thanks I think they hooked the bathroom exhaust vent into the vent stack pipe in the attic
Who is "they".

Preveious owners of the home

Must have been petty dumb.

Can man,
In a tightly constructed home it is possible for the dryer exhaust fan to create negative indoor pressure and draw in outdoor air through vents, fireplaces, exausted appliances / furnaces / water heaters, etc.
If your bathroom vent exits near the soil pipe vent, sewer fumes could be drawn in when the dryer runs - I would first confirm that sewer gas is present by opening the soil pipe clean - out in the basement. There are many ways to generate odors similar to sewer gas including dead, rotting rodents...