Oxygen Sensor Signals

Oxygen Sensor Signals

The sensor conductivity is efficient when the oxygen sensor is hot (750 °C). For this reason, the sensor contains a heating element. This reduces warm up time, and retains the heat during low engine speed when the exhaust temperature is cooler. The oxygen sensor healing element receive power from the IVM (12 V) and the ground supply is pulse width modulated by the ECM.

The monitored voltage signal is constantly changing due to combustion variations and normal exhaust pulsations.

- At a value of Lambda 1,the pump cell requires approx. 3 mA.
The oxygen sensor signal voltage is approx. 1.5V
The reference cell voltage is approx. 450mV
- At a Lambda value < 1 (rich), the oxygen sensor signal voltage is approx. 0.3V
- At a Lambda value > 1 (lean), the oxygen sensor signal voltage is approx. 4.3V

If necessary, the ECM will "correct" the air/fuel ratio by regulating the ms injection time. The ECM monitors the length of time the sensors are operating in the lean, rich and rest conditions. The evaluation period of the sensors is over a predefined number of oscillation cycles and pump cell amperage.