Fault criteria, oxygen sensor 1
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Fault criteria, oxygen sensor 1
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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.
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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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Coolant temperature above 60C (140F)
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Sensor preheating current below 1500 mA
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1.
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Count:
- number of sensor transitions
- number of engine revolutions
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2.
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> 12 sensor transitions during 265 engine revolutions
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3.
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Diagnosis performed during this trip
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4.
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Fault criteria for oxygen sensor 1, transition diagnosis fulfilled
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5.
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Third attempt to approve sensor
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6.
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Next occasion conditions for diagnosis are fulfilled during this trip
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