Knock Sensor

Any one know where is it located and have a picture or diagram of the 'knock sensor' on the NB? I have CEL 0325, 'knock sensor failure'. I understand it should on the engine block in passenger side under the intake manifold!? Anyone know how $$$ for a new one?

About 130 dollars at rockauto.com for a 99 Miata. Not sure of your exact year.

I can't get on any of the parts websites right now so can't check NAPA, or Autozone, or O'Rileys but usually Rockauto is cheaper even with shipping.