Firstly, it would have been more helpful to have explained what the code meant. Few people will have memorised any codes, so will have to look it up, or just not bother, so you restrict the help you may get. You've understood what it means, but chose to keep that a secret.
Moan over.
The code relates to the cat output not being as expected. The second sensor, there as a check, is not getting the results it expects.
Cats do not fail as often as people think, they are very reliable and will usually outlast the car. They are susceptible to damage, or contamination. Earlier units, fitted under the car can be damaged if struck, on raised objects, animals, etc., but with most being now at the manifold, that is unlikely, unless the car has sustained frontal accident damage, which damaged the cat, and the cat not changed. Contamination would usually be from excess oil burning. Unless any of these apply, the cat is probably ok.
That leaves the sensors.
Need a proper diagnostic program, like
MultiECUscan (
MES) to show the readings of both sensors. It is likely that either or both sensors are failing, which is a simpler, cheaper job. Meanwhile, check the wiring to both sensors for any damage or poor connections.