had the recall done on cam sensor,anyone know why there are no codes stored

1,pt.no.114036

2,v-7r19d

3,2002,ford f250 7.3 diesel
since installing the tow tune i had the engine light come on when going up hill with my 24ft trailer,it would run like crap loss of power the light would go out and would be ok till the next hill there was never any codes present i took it to a ...