Correct me if i'm wrong but knock sensor does serve a purpose to the ecu.It got something to do with the engine temp that link to ecu and the knock sensor.I was adviced by a honda tech person that you can still run the car without the knock sensor but not on the long run as it'll damage the engine.Anyway...i did broke my knock sensor when i fixed up my supercharger kit...then bought a new unit for crv...smaller a bit but still usable..about RM350 if i'm not mistaken..just for the knock sensor.Anyway...it's located below of the intake manifold..near to oil filter.Cheers and happy rexxing!