Reluctor/Magnetic sensors have a toothed trigger wheel that passes across the face of the sensor. The movement of the teeth past the sensor generates a voltage in the sensors winding. These sensors usually have only two wires as the sensor itself generates a voltage. One wire is the sensor ground while the other is the signal output. Some reluctor sensors have a second ground to sheild their enclosure and therefore have three wires. These sensors are often identified by sharp tooth profiles.

Reluctor sensors MUST be wired so that the ECU sees a positive voltage as the tooth approaches the sensor and a negative voltage as the tooth leaves the sensor. An oscilloscope is usually required to determine correct reluctor polarity.