Patent ID: 7311093

Claim:
An element crack detecting apparatus for an oxygen sensor which is disposed in an exhaust system in an engine and has an oxygen sensing element, an exhaust-side electrode and an atmosphere-side electrode, the detecting apparatus comprising: a negative voltage detection means for detecting a potential difference between the exhaust-side electrode and the atmosphere-side electrode as an output voltage, the negative voltage detector being used in an engine control apparatus for determining a fuel injection quantity to the engine based upon a detection value to determine whether the output voltage is a negative voltage for an abnormality detection period after a fuel cut-off to the engine is started during operation of the engine; abnormality determination means, which determines whether an element crack abnormality is present in the oxygen sensor based upon a determination result of the negative voltage detector; and abnormality detection condition setting means for allowing the abnormality determination means to start determining the element crack abnormality after a start of fuel cut-off to the engine.