To accurately detect the amount of hydrocarbon adsorption and amount of moisture adsorption to the zeolite of a hydrocarbon adsorbing device even while an engine is operating.
A hydrocarbon adsorption amount sensor 10 for detecting the amount of hydrocarbon adsorption to the zeolite 12 of a hydrocarbon adsorbing device 4 to adsorb hydrocarbon in exhaust gases by zeolite is provided with both a plurality of electrodes 13 and 13 provided opposite to each other in the vicinity of the hydrocarbon adsorbing device 4 to carry zeolite and a sensor circuit to detect the amount of hydrocarbon absorption by a parameter which indicates changes in at least one of the resistance value and electrostatic capacitance Cs between the plurality of electrodes 13 and 13.
IWAKI YOSHIHISA
HAGA TSUYOSHI
ENDO TETSUO
UENO MASAKI
YASUI YUJI
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