code po140b

My previous post "driveability problem" didn't generate the response that i thought it would. so here's more info. the ses light is mostly staying on and when scaned shows code P0140b. When light is on it actually runs better than when it's off. any ideas!! :banghead:

The P0140 code has to do with the Oxygen sensor no activity Bank 1 Sensor 2. As for the at the end nothing I have with codes gives the b designation.