Ngk Spark Plug Company, Limited

Koji Nagura

Shuichi Hanai

Kenichiro Umemoto

When an internal combustion engine () is determined to be in a low-temperature start state (an affirmative determination is made in S), an air-fuel ratio control apparatus () controls the temperature of a downstream detection element () of a downstream gas sensor () to a downstream target temperature by driving a downstream heater () of the downstream gas sensor () (S), and feedback-controls the air-fuel ratio of exhaust gas based on the output of the downstream gas sensor () (S). When the engine () is determined not to be in the low-temperature start state (a negative determination is made in S), the air-fuel ratio control apparatus () drives an upstream heater () of an upstream gas sensor () and feedback-controls the air-fuel ratio of exhaust gas based on the output of the upstream gas sensor () (S).

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Kasugai, Japan

Koji Nagura