Bertha

I have a 2004 Silverado. It has 117,000 kms and in the past 2,000 kms its been having issue after issue. Before that, it's had no major issues. My engine light comes on constantly. I check my codes and it alwayscomes up as a Knock Sensor. It doesn't seem to run rough, though I have noticed a slight lack of power.Does anyone have any ideas why this code could be coming up? I've had the sensor checked and it seemed to be working fine.
Also, my truck burns through O2 sensors like it was its job. Any ideas about why this would happen as well?