To accurately determine abnormality of signal wiring for a plurality of exhaust gas sensors with input connections into an engine control unit.
Positive terminal electrical potentials of the exhaust gas sensors 103a-103d are selectively inputted in sequence into an analog input terminal of a multi-channel AD converter 114 via a multiplexor 130. An offset voltage V1 is applied to each negative terminal of the exhaust gas sensors 103a-103d, and the offset voltage V1 is inputted into another input terminal of the multi-channel AD converter 114. A microprocessor 110 detects generated voltages of the exhaust gas sensors 103a-103d by a difference between a digital conversion value D2 of the positive terminal electric potential and a digital conversion value D1 of a negative terminal electric potential, and too insufficience/excess of each digital conversion value D1, D2 is individually determined to determine existence or nonexistence of a grounding/discharging/wire breakage abnormality of the negative terminals and positive terminals.
TANAKA TORU
YOKONO MICHIHISA
FUKUI AKIHIRO
MATSUDA YUSUKE
Toshihide Kodama
Takenaka Ikuo
Keigo Murakami
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