Every time we tow our hybrid when we get to the site or get home we had a bad sewer odor in the camper. Just open windows and turn on the fan and its gone in a few minutes. I've tried towing with the ...
Check under your sinks and look for a vertical pipe with a black plastic vent looking device. If you have one, it is a vacuum breaker that allows the gray tank to vent. Sometimes these one way vents are not threaded on tightly or defective, allowing tank vapors to enter the cabin. I had that problem once, tightened the vent and no more odors