9-3 Convertible (9400) L4-2.0L Turbo (2.0 HOT) (2003)
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The oxygen sensor comprises a primary cell with a solid electrolyte. The electrolyte consists of a tube of ceramic zirconium oxide with concave ends and
its temperature is stabilized by the addition of a small amount of yttrium oxide. Its surface is coated with titanium and therefore conducts electricity.
When the motor runs on a lean mixture the oxygen content of the exhaust gases increases. The oxygen sensor voltage then drops and the engine control
module reacts by extending the injection time. At a closed-loop value of 1.0 the voltage is about 0.45 V.
The oxygen sensors are effective only when their working temperature exceeds 600 °C (1120 °F) and are therefore provided with electric pre-heating.
The pre-heating on cars with TRIONIC is controlled by the control module. A relay has been used on certain markets to disconnect the pre-heating when
the engine speed exceeds 3000 rpm as the oxygen sensors are then heated by the exhaust gases. The output signal diminishes with the age of the oxygen
sensors and the sensors must therefore be changed after 160 000 km (100 000 miles).
