when i bought my em1, it had a b18c1 swap due to theft but the previous owner was running it the Si ecu.. i bought a obdII p72 but it doesnt work with it for some reason.. immobilizer or something.. can any1 tell me what a knock sensor is and if that would solve my problem? if not then should i invest in a conversion harness and get a obdI p72?

 

It doesn't work cause of the immobilizer and a couple wires need to be switched

 

and the knock sensor?