You would have to manually check fuel pressure with a gauge to figure that out, I would suspect that you would have running issues or other codes that point to a lean condition if low fuel pressure were the case. A fuel pressure concern would also effect both the left and right banks of the engine equally so you would end up with a code from the other downstream oxygen sensor. The key here is going to be checking fuel trim data and watching the voltage readings the sensor is giving. You may need to consult your mechanic so it can be hooked up to a scan tool