Description 4age 20V Blacktop – Knock sensor This small single pin sensor detects engine knock / detonation. it is located on near the top of the engine block between the third and fourth cylinders on the intake side. Suits the “Blacktop” / AE111 series of engines only, is not compatible with the earlier Silvertop engines. Additional information – Thread specifications: M12 x 1.25mm
