Are you 100% sure its the knock sensor? what management are you runing cause when i was runing the power fc in my old glanza the engine management light was flickering through the revs not on tick over and it was doing it because i was useing shit fuel it sounds silly i no but the ecu was mapped for hi octane fuel so when i put shit fuel in it change the timeing and the ecu didnt like it if you get me lol