S trap situation and air admittance valve?

[rmflint]

This is a picture of the drain plumbing under my kitchen sink. I have been noticing sewer smells inside our cabinets. I removed and cleaned the p trap pipes and they were not dirty. The sink drains fine.

I am thinking the way it hooks up to the septic drain line has created an s-trap situation.

The drain pipe is vented through the roof behind the wall.

Would adding an air admittance valve (AAV) be a recommended solution?

 

[breplum]

Yes. to note: Code requires kit. sink drains to be 2". and drainage fittings to be used...what i see is a elbow made for pressure pipe and no required cleanout. Idiots who are not plumbers did this work so there you go.

 

[TomFOhio]

And the vent on top of the tee looks reduced down.