my check engine light went on because my knock sensor is busted. the light goes on one day and goes off the other day. my question is, how bad is it not to change the sensor? i know my gas consuption would suffer, how much worse? if the light goes on one day and goes off the other day, does it mean it still works, but bad connection? what should i do in this situation? how hard is it to change it? i have 98 millenia 2.5L, thanks in advance

 

come on people, please help me with this issue, i will greatly appreciate it!