That line goes to the charcoalo evaporative canister (both lines go there).
If one was broken, bet the others are chracked and broken, also.
Check the corrigated intake hose, flame trap hoses, idle air control bypass hoses for leaks, as well as the intake manifold gasket. It's probably a good time to replace every hose if they are original.
That code doesn't necesarilly mena the O2 sensor was bad, most often is vacuum leaks, Replace the sensor only after you know the leaks are fixed.