roshedomv2

I recently just installed a catback system on my 07 is250. At first the car was initially fine but after about 50 miles of driving the CEL/VSC light came on. The code I got from it was P0137 bank 1 sensor 2, o2 circuit low voltage which I think is the passenger side sensor that connects into the exhaust system. The sensor was fine until I replaced the exhaust system so it looks like it was on the verge of going bad when it was disconnected and reconnected into the new system. But just to make sure, Is it just that sensor went bad or is it something else? Also if it is that sensor issue, what would be the part number for that sensor I would need to get? Thanks