I had the equivalent code on my Ford. Please follow Klaus' advice and check for other codes then address them before suspecting or investing in the cat. Also look for an exhaust leak even if very small which can upset the flow to the oxygen sensors (as well as vacuum leaks etc). These things could act like a failing cat.

I got the catalyst efficiency code once in a while and reset it. This car has 2 cats with separate efficiency codes. One code would set, then the other in a little while. This pattern would return after a month or 2. Eventually it showed up more and came to the point that the codes would come on after just a day or 2.

I thought it was unlikely both cats would go bad at once so I looked for everything else I could think of first. Finally I had the 2 catalytic converters replaced. No codes of any kind have come back so far (4 months).

The car had only 75K miles and I thought that was early for cats. On the other hand the engine had a history of running rich which would contaminate the cat, and the engine on this model is not known as one of the world's most efficient designs. People tell me the cat CAN be a lifetime component but may not be.