Abstract: A control installation for the dosing or proportioning of a secondary air quantity for the improvement of combustion in internal combustion engines, or the afterburning of the exhaust gases of internal combustion engines, including an auxiliary arrangement which is responsive to an emergency signal for effecting the prompt shutting-off of the secondary air. The emergency signal may be initiated in response to a failure in the ignition voltage of the internal combustion engine; an increase in the hydrocarbon content of the exhaust gases; a disparity between the position of the mixture dosing element and the engine rotational speed; the exceeding of a limiting temperature in the exhaust gas manifold; or the exceeding of a limiting temperature in the afterburner.