I have a 2005 Mandalay 40B and have owned since 20,000 miles, has 34,000 now. It has always had a bit of a sewer smell when driving. I do not run with vents open, both tanks have been bleached but o...
Finally, check the "P" trap in the washer....if you haven't used the washer in awhile, the water evaporates and will allow a sewer smell back into the coach....Dennis