This paper describes a dual-track magnetic crankshaft and camshaft position sensor configuration. It uses semiconductor sensors such as magnetoresistors to pick up the magnetic flux modulation created by a toothed wheel rotating across a permanent magnet. This sen-sor's magnetic configuration, with a complementary geometry, enhances the accuracy and repeatability of the position pulses. This is critical in obtaining the engine-velocity measurement precision necessary to detect engine misfires as mandated by the OBD-II legislation. The complementary geometry also makes for a more robust design. Finally, the concept can be used for cam-shaft position sensing, with power-on capability.