“At all other times during normal vehicle operation, the ‘switch’ was activated and the vehicle ECM software ran a separate ‘road calibration’ which reduced the effectiveness of the emission control system. As a result, emissions of NOx increased by a factor of 10 to 40 times above the EPA compliant levels, depending on the type of drive cycle (e.g. city, highway).”
All US vehicles must be issued with a certificate of conformity that proves they adhere to environmental standards.
To obtain a certificate of conformity, a manufacturer must submit a list of all auxiliary emission control devices (AECDs) present on the vehicle. The EPA’s definition of an AECD is “any element of design which 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.”
The issue facing Volkswagen is the switchable system in the ECM was not declared.
“Due to the existence of the defeat devices in these vehicles, the affected Volkswagen vehicles do not conform in all material respects to the vehicle specifications described in the applications for the certificates of conformity that purportedly cover them,” said the EPA.
A defeat device is an AECD “that reduces the effectiveness of the emission control system under conditions which may reasonably be expected to be encountered in normal vehicle operation and use. Motor vehicles equipped with defeat devices cannot be certified.”
Read more on the Volkswagen emissions scandal:
How the Volkswagen story unfolded
VW board anticipates more top-line casualties
European cars are affected, says German minister
PSA Peugeot Citroën leads calls for tougher emissions test procedures
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