Our master bathroom has a strong sewage smell. The bathroom is located on the second floor, and the house is 8 yrs. Old. Our two other bathrooms have no such smell. Thorough cleaning of the toilet, candle-burning, and turning on ventilation, doesn't help. We've lived in the house for about two months, and the smell is getting stronger. What may be causing this smell? Vent Clog? How would I check this? Sewage pipe leak inside wall? Thanks.

You may first want to make sure the vent pipe (going through the roof) is not plugged. If it is, you may be siphoning the water from your traps which would allow the gases to come back up. You may be able to check a couple of different ways. The easiest may be to have someone flush the toilets other bathrooms while you watch the water in the one in the master bath. There should be no movement of the water in the bowl. The other way involves going up on the roof and looking down into the vent.
Has the smell always been there or start later?

Thank you so much for your response. We did the flush/movement test. And there is a slight movement of water (shaking, no bubbles) in the other toilet on the second floor!! What should I do next? I can not check the roof vent until my husband gets back from his trip. I appreciate your answer very much.

"What may be causing this smell? Vent Clog? How would I check this? Sewage pipe leak inside wall?"

Another cause of the sewer gas escaping could be the wax seal on the flange. Sometimes they will contain water but not air so that every time you flush it lets out a puff of sewer gas and when it's just setting the gas escapes slowly into the bathroom. This condition is more common then you would think. Just another option to look into. Tom