sleeve cover over the cat sensor wire frayed

Had my 2001 Barchetta on the lift today to do a pre season inspection. Noticed the steel braided sleeve that covers the Cat sensor wire for one of the two cats was frayed. It Exposed the tiny wire inside the sleeve. I wrapped the frayed area in electrical tape as a temporary fix. When I took the car out for a drive the Slow down light was coming on and off. It eventually stopped coming on. Questions:
What happens if you just have a wire malfunction?
How much is a new wire and the sensor that attaches to it?
How simple is the replacement if you have your own lift and tools?
Any danger in driving the car that way for a while until I get the replacement wire?
What typically causes this wire to fray?The other wire for the other cat looped right next to it was perfectly fine. Mice? Snagged it on something? Any past experience?
PS a search didnt answer these specific questions on a 550
Thanks Jon in Delaware

 

Got any photos?

 

Scott,sorry I didnt take any. Anyone that has a 550 and has walked under it on a lift cannot miss the Cat sensor wires. They loop together and are exposed under the car right at the cats. you can see how they attach to the cats with a bung or plug.