All B18C1's had knock sensors. Any Honda engine that requres premium fuel will have a knock sensor (that's the engine's way of telling if you cheaped out on gas to protect itself). The sensor is on the back of the engine by the oil pressure sensor and oil filter. That wire will have to be run to D3 on the ECU to get rid of the error code. Since the ECU can't get a signal from the knock sensor, it will most likely put itself into limp mode (richer, less aggressive fuel maps to protect itself from low octane gas) and your car will have less power.