Kia Rio heavy steering c1688 code

hi posted while back about steering some1 sent link its not the plastic cogs thats in steering rack this model doesent have them but this code came up c1688 wehicle management (vsm)2(mdps) signal error does any one know what this could be sometime the steering comes back for a bit then starts to go again to heavy had new eps moter fitted still does the same had new battery betlts alternator still doing this any advice be greatfull thanks in advance