Help with O2 sensor problem

Took the 2003 ZX5 in for a vibration problem in reverse. Turns out
the motor mounts are shot. They ran a diag and found that the O2
sensor is bad and also some vacuum hose assoiated with the sensor had
a hole worn in it. I know that a two conductor cable runs to the O2
sensor. They want $288 to fix the O2 problem. I can get the sensor
for $50 and $10 for the special socket to remove it, but anyone know
what they are talking about the vacuum hose?

Thanks
Jay