Modern cars with diesel engines are equipped with the selective catalytic reduction system (SCR) which ensures the significant reduction of the harmful nitrogen oxide content in the car exhaust and the compliance with the toxicity norms Euro-6.
SCR technology is already used for the commercial transport, tracks and buses. However, the passenger car owners can be surprised that such system is implemented in their cars.
SCR technology is used in the passenger cars in different versions. Company Mercedes names this technology BlueTec, VW - BlueTDI, BMW - BluePerformace Technology.
General configuration of the SCR/Adblue system can be examined by example of the VW car equipped with the engine 2.0 BlueTDI (see Fig. 1).
Fig. 1 Configuration of SCR/Adblue system
Solution Adblue is pumped under pressure from the urea tank through the pipeline to the urea nozzle which injects the dosed amounts of the solution into the outlet duct. Reducing catalyst promotes the chemical reaction resulted in conversion of the harmful nitrogen oxides NOx into the harmless N2 (nitrogen) and H2O (water). Efficiency of the system operation is determined by NOx sensor at the outlet of the reducing catalyst.
However, the owners of such cars face the additional difficulties during operation. With this system installed in the car the regulatory norms for the exhausted gases toxicity forbid the engine restart in case of lack of the Adblue solution in the tank or in case of the system components failure. Upon detection of the system error the information screen displays a message about the mileage or number of starts left (see Fig. 2).
Fig. 2 Example of the message about the mileage left
After the car has passed this distance or used the number of starts left it can only be restarted after the reset made by the diagnostic scanner, but even this will increase the driving distance only by 50 km. In most cases the maintenance or the repair of this system is too expensive and does not match the current economic realities of our life.
Switching the SCR system off allows to avoid necessity in refilling of the Adblue solution. After the SCR system is switched off the start blocking as well as the mode of the power output limitation due to the failure of some system components will be disabled.
At present time our company offers the turnkey tested solutions for the software switch-off of SCR/Adblue system in cars BMW X5/X6, Mercedes Benz ML/GL/Sprinter, Mazda CX7/CX9, VAG Group (all models).