40 CFR 86.409-78 - Defeat devices, prohibition.
(1) Senses temperature, vehicle speed, engine RPM, transmission gear, manifold vacuum, or any other parameter for the purpose of activating, modulating, delaying or deactivating the operation of any part of the emission control system and
(i) Such conditions are substantially included in the Federal emission test procedure, or
(ii) The need for the device is justified in terms of protecting the vehicle against damage or accident, or
(iii) The device does not go beyond the requirements of engine starting or warm-up.