A report from German newspaper Bild am Sonntag states that US Department of Justice has claimed that engineers from Mercedes Benz parent company Daimler has been accused of using software programs to tweak emission statistics in their diesel models.
This allows the diesel models to pass US emission tests but only for a limited period of time after which the true emission standards emerge which is way above specified limits.
This software program allowing diesel models to cater to US emission norms through manipulation of engine and selective catalytic reduction filter, adopted by Mercedes Benz, are on the same likes as those which were developed by VW. The information received by Bild am Sonntag finds that software programs have been developed complying to “Bit 13” function.
This allows the engine to run in clean state for a very limited period of time and then to revert back to dirty mode after 16 grams of NOx are emitted. This is precisely the duration of US highway testing cycle. “Bit 14” software function is also being used to switch engine to dirty mode under specific temperatures and time periods which have been preset. This allows cars to pass FTP-75 warm test cycle.
The car and equipment which brought to light VW Dieselgate scandal. Mercedes is allegedly running a similar patch in their engine. Image – West Virginia University
“Bit 15” is another software function being used during US06 test cycle which has been programmed to switch off the SCR exhaust gas after treatment system after 16 miles. Slipguard is yet another software function being used on various Mercedes Benz models. This system detects when the car is being tested on a rolling road.
It allows for a specific dosage of urea based AdBlue solution within the SCR exhaust gas after treatment system thus allowing the vehicle to comply with emission standards set. Investigations into these allegations are underway while Mercedes Benz has avoided issuing any comments.