9-3 Arc/Aero (9440) L4-2.0L Turbo (2.0 T) (2004)
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In order to quickly generate a signal after start the oxygen sensor must be preheated. In order to control the heating effect the grounding of the circuit is
pulse width modulated.
The preheating is activated as soon as the coolant temperature exceeds 30 degree C.
The control module estimates the exhaust gas temperature on the basis of load and engine speed. At high temperatures the preheating is disconnected to
avoid damaging the oxygen sensor.
If the catalytic converter is damaged its oxygen storage capability is reduced. The normal swings in the lambda control will then be noted from the
voltage signal of the second oxygen sensor and a trouble code will be set. The catalytic converter is checked once every drive cycle.
