Oxygen Sensor: Description and Operation

Fig. 74 Oxygen Sensor with Internal Heater:

An oxygen (Lambda) sensor Fig. 74, is used to provide more precise control of air/fuel mixtures. This system operates by measuring oxygen content in exhaust gases, as the amount of oxygen remaining in the exhaust gases is directly proportional to the air/fuel ratio of mixtures entering the engine. The sensor, mounted in the exhaust stream, reacts to the oxygen remaining in the exhaust gases and produces a variable voltage signal (0-1.0 VDC) depending upon the oxygen content.
The oxygen sensors on cars with KE-Jetronic injection have an internal heating element built into the sensor. These can be easily identified by three wires connecting to the sensor, rather than one as on the K-Lambda systems.