2008 Acura TSX P2271

Hi,
2008 Acura TSX – K24A2 Engine
Mileage – 230,000 km
P2271 – O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2

For the past one week I’ve been getting a P2271 error code on my car. I’m trying to gather as much information as I can before making any repairs. I’m not noticing any power loss, but I think there’s a gas smell from the exhaust when I go to start the car. The error says it’s running rich but I thought I’d notice it with the fuel consumption but after driving about 200km I still average about 8.4L/100km. Any advice on what to do would be much appreciated. Could it be my catalytic converter on its way out? Should I just replace both downstream O2 sensors?