hi
my 2001 neon has the following codes, how can i make them go away??

P1684 Battery Was Disconnected
P0340 No Cam Reference Signal at PCM or P0340 Camshaft Position (CMP) Lost
P0551 Power Steering Switch Failure

i have no clue what i have to replace to make them go away. or at least clear the codes to see if they come back on.... help!

 

First one is a dumb code that means nothing
Second: likely either a bad sensor and/or wiring
Last: same as the other