Procedure and equipment for monitoring the operational readiness of an oxygen probe

摘要

The mixture control system of an internal combustion engine which employs an exhaust gas oxygen sensor is provided with circuitry which subjects the output signal from the sensor to comparison with established threshold values to determine the operational readiness of the sensor. When the amplitude of the sensor signal is sufficiently high, indicating proper operational temperature of the sensor, the test signal is turned off and the monitoring is taken over by a circuit which looks for regular alternation of the sensor signal at a sufficiently rapid rate. When the sensor signal is found inadequate for any reason, the closed loop control system is disengaged and the mixture control is provided on the basis of an average sensor voltage supplied by the circuit.