On-board diagnostic test of oxygen sensor
First Claim
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1. A method for determining performance of a heated exhaust gas oxygen (HEGO) sensor, including the steps of:
- monitoring nonintrusively a HEGO output voltage trace with respect to time;
summing the HEGO output voltage trace over a specified completion criteria;
establishing a predetermined threshold completion criteria for the sum of the HEGO voltage; and
comparing the summed HEGO output voltage against said threshold completion criteria to determine if the HEGO meets predetermined performance requirement specifications.
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Abstract
An on-board diagnostic test for an exhaust gas oxygen sensor includes sensing the output of the oxygen sensor and summing the output over a specified period to determine the length of the trace of the sensor voltage versus time. Such length over a given time period indicates the activity of the sensor. This data is compared to a threshold to determine if the exhaust gas oxygen sensor meets certain performance requirements.
16 Citations
9 Claims
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1. A method for determining performance of a heated exhaust gas oxygen (HEGO) sensor, including the steps of:
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monitoring nonintrusively a HEGO output voltage trace with respect to time; summing the HEGO output voltage trace over a specified completion criteria; establishing a predetermined threshold completion criteria for the sum of the HEGO voltage; and comparing the summed HEGO output voltage against said threshold completion criteria to determine if the HEGO meets predetermined performance requirement specifications. - View Dependent Claims (2, 3, 4)
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5. A method for determining performance of a heated exhaust gas oxygen (HEGO) sensor, including the steps of:
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establishing entry conditions for beginning the method for determining performance of a HEGO sensor; determining that the entry conditions have been met; sensing a voltage output from the HEGO sensor; summing the voltage output from the HEGO sensor over a specified time interval; establishing a predetermined amount of voltage data to be collected; determining if the predetermined amount of voltage data has been collected; if the predetermined amount of voltage data has been collected, normalizing the collected data with respect to the tip temperature of the HEGO sensor; calculating a HEGO index values; establishing a failure index value; comparing the HEGO index value to the failure index value; and if the failure index value is greater than the HEGO index value, indicating the occurrence of a malfunction. - View Dependent Claims (6)
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7. A method for determining performance of a heated exhaust gas oxygen (HEGO) sensor, including the steps of:
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monitoring nonintrusively a HEGO output voltage; determining a length index as a function of the actual length of the trace of the HEGO output voltage versus time over a specified period; establishing a predetermined threshold for the length index of the trace of the HEGO voltage versus time; and comparing the actual length index of the trace of the HEGO output voltage against the predetermined threshold for the length index to determine if the HEGO meets predetermined performance requirement specifications. - View Dependent Claims (8, 9)
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Specification