Supra L6-183 2997cc 3.0L DOHC (2JZ-GE) (1993)
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Oxygen Sensor: Description and Operation
PURPOSE
Two oxygen sensors, a main and a sub, measure the oxygen content in the exhaust and send a voltage signal to the ECM.
CONSTRUCTION
Each sensor consists of a steel housing, sensor tip, its protective sleeve and an internal heating element. The sensor tip itself is made from a
platinum covered zirconium-oxide pipe.
OPERATION
The oxygen sensor produces a measureable voltage by comparing the amount of oxygen in the exhaust gas with the amount in the ambient air.
The sensor operates only within a certain temperature range of approx. 285 - 850°C (545 - 1530°F).
The exhaust gases reach the outer surface of the oxygen sensor tip via the openings in the protective sleeve. Ambient air reaches the sensor's inner
surface via channels. The differance in oxygen content produces a voltage read by the ECM.
The heating element is controlled by the ECM. When the sensor is cold the ECM grounds the circuit, causing the sensor to heat. The electric
heater allows the sensor to reach operating temperature much sooner than it could simply by using exhaust gas to heat it. The heater also prevents
sensor cool-down during periods of extended idling.