Abstract: A compact reversing flow catalytic converter with protection from overheating includes a valve unit which directs exhaust gases through a container filled with catalytic material to permit a bypass of catalytic material when a temperature of the material exceeds a predetermined threshold. The container defines a U-shaped gas passage that communicates with two ports at the top of the container. The valve unit is mounted to the top of the container and includes an intake and an exhaust cavity. The valve unit includes a valve disk having two openings therethrough. The valve disk rotates around perpendicular central axis between a first, a second and third positions. When overheating of the catalytic material is predicted, a controller relinquishes control of the valve disk and a center return mechanism rotates the valve disk to a third position, in which each of the openings communicates with both ports so that the exhaust gas flow bypasses catalytic material.