If my car smells like weed?

I dont smoke weed anymore. I took my friend home from work...he was smoking weed in my car and obviously it smelled.. if a cop pulls me over for anythin, like missin tail lights, etc. and he smells my car...ask me if i been smokin and i dont smoke...maybe check my car for weed even have K9 searching it..i told him my friend was smoking weed in my car...could I get in trouble? what will happened?