That is what the code is for so what is it how much does it cost and what causes it to go bad? HELP

 

What is it? Detects combustion knock (the next step above ping).
What does it do? Retards ignition timing until the condition clears.
How much is it? Depends on were you buy it.
What causes it to go bad? My crystal ball is not working at the moment.
Where is it? Usually it's in the valley under the intake manifold.
Be sure it not the plug.