Shows code P0171 bank 1-Combustion too lean,P0420-catalyst eff. too low, P0174-combustion to low, what is the possible problems & costs?

Tar Heel Person>>>p0171/p0174 are lean codes.could be a vacuum hose leak,intake leak,dirty or bad MAF sensor, or a number of other things.As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.