摘要 |
A method and apparatus for detecting when the internal resistance of an oxygen sensor is too high for useful signal processing. A reference voltage is applied to the sensor signal to generate a test voltage which is compared with two different threshold voltages. The three possible magnitude states of the test voltage with respect to the thresholds cause the comparator output signals to define logical conditions which are processed by logical gating circuitry to inhibit a timing circuit which otherwise would switch fuel mixture preparation from sensor-controlled operation to open-loop, direct control after a period of time.
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