Oxygen Sensor: Description and Operation

Fig. 6 Lambda sensor, typical installation.:

The lambda sensor, Fig. 6, measures the amount of unburned oxygen in the exhaust system. Large amounts of oxygen indicate a weak mixture, whereas small amounts of oxygen indicate a rich mixture. A signal is sent to the ECU to compensate for these variations by constantly adjusting the duration of the injector pulse. A service indicator counter and service indication lamp are used to indicate when the lambda sensor should be changed.