Search the forum for diagnosing those codes before spending money on sensors. Both banks running too lean makes me think that the engine is actually running too lean rather than thinking those oxygen sensors failed at the exact same time.

 

100% agree. Unlikely to be O2 sensors at fault. Codes simply mean the system could not richen up the system enough to obtain the desired fuel:air ratio on either bank of injectors. How about a bad fuel pump or bad fuel pressure regulator. Start by checking pressures and eliminating these.