9-3 SE Sedan (9400) L4-2.0L Turbo (B204) HO (1999)
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The ability of the oxygen sensor to react quickly to changes in the fuel/air mixture is diagnosed once per trip. When conditions for the diagnosis have
been fulfilled, the sensor transition frequency will be measured. Transition is when sensor voltage goes from high to low or from low to high. The sensor
is defective if the transition frequency is too low.
The number of sensor transitions is counted for 265 engine revolutions. If the number exceeds 12, the diagnosis will be approved.
If the number is below 12, another two attempts will be made to obtain an approved diagnosis during this trip. If the sensor test is negative on all three
occasions, the fault criteria will have been fulfilled.
Otherwise, the sensor and its preheating is monitored according to OBD I.
Conditions for diagnosis
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Diagnosis not yet performed during this trip
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Engine running for longer than 3 minutes
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Vehicle Speed = 0
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Idling speed
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Closed loop activated
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Coolant temperature above 60C (140F)
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Sensor preheating current below 1500 mA
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No load changes
