Control device for exhaust gas control apparatus

A control device for an exhaust gas control apparatus provided in an exhaust system of an internal combustion engine configured to change an air-fuel ratio, the exhaust gas control apparatus including a catalyst configured to remove at least NOx from exhaust gas, the control device being configured to perform control for catalyst de-poisoning when the catalyst is poisoned, the control device comprising a controller configured to perform catalyst de-poisoning control on the catalyst based on a result of detection of NOx downstream of the catalyst,

• wherein the controller is configured to
• determine that a degree of poisoning of the catalyst is a large degree when a detected value of the NOx is greater than or equal to a first reference value determined in advance,
• determine that the degree of poisoning of the catalyst is a small degree when the detected value of the NOx is smaller than a second reference value determined in advance,
• set the air-fuel ratio to lean when the degree of poisoning of the catalyst is determined to be the large degree, and
• stop supply of fuel to the internal combustion engine that is rotating, when the degree of poisoning of the catalyst is determined to be the small degree.