call a licensed proffesional...and if this is a mobile home make sure the company you call works on them

The vent should be in the wall somewhere, not visible in the cabinet. Does the sink gurgle and drain funny? If so maybe there's no vent. I've lived in several houses with unvented plumbing. As long as it drains, I'd live with it. BTW, if that's a dishwasher hose, it should be looped up high in the cabinet.

well there is definitely a vent in the basement, but shouldn't there not be an "s" trap but just a P

When you have to go down through the bottom of the cabinet that's how it's done.

"The vent should be in the wall somewhere, not visible in the cabinet."

Wrong. It's called a Studor and is located between the trap and wall. Quite visible in the cabinet. Inspection allows them when the trap is too far from the main stack/vent.

Joe, thank you. the studor is an AAV, similar to what everyone calls a cheater vent right?
However, down in the basement it doesn't look like it goes to a vent stack unless that's the same pipe the waste goes out.

It appears that you have an S trap (no longer allowed) and it does not have a vent. A Studor vent would work to fix a vent problem, but you still have an S trap.

The risk with an S trap is that suction from water going down the drain may pull the water out of the trap and leave you exposed to sewer gas. A P-trap with a vent (either a vertical pipe in the wall or a Studor) keeps this from happening.

Bruce

thanks Bruce, Im just having trouble working out how to. do the p trap with the studor and still have it exit the floor and not the rear of the cabinet.