To provide an abnormality determining device of a water temperature sensor capable of correctly determining not only the abnormality of a large characteristic deviation but also the abnormality of a small characteristic deviation.
Any abnormality of a water temperature sensor 21 for detecting the temperature of cooling water of an internal combustion engine is executed by the first and second abnormality determinations. In the first abnormality determination, the generated calorie Q_HG of the internal combustion engine 3 is calculated as the calorie given to cooling water from the start, and when the detected value TW of the water temperature sensor 21 is lower than the predetermined temperature TREF after the generated calorie Q_HG reaches the predetermined value QREF, it is determined that the abnormality of a large characteristic deviation occurs in the water temperature sensor 21 (Steps 16, 18). The second abnormality determination is executed when it is determined by the first abnormality determination that the water temperature sensor is not abnormal. When the operation time TM_FON of a radiator fan 15 is larger than the predetermined threshold TJUD, it is determined that the abnormality of a small characteristic deviation occurs in the water temperature sensor 21 (Steps 48, 50).
MIYASHITA KOTARO
OZAWA TAKAYUKI
KAWAMURA KAZUNORI
