AdBlue and Selective Catalyst Reduction (SCR)

The AdBlue and Selective Catalyst Reduction system (SCR), is being increasingly fitted on modern diesel cars and light vans, in preparation for the new euro 6 emission standards. This system has been in use for quite some time in heavy goods vehicles.

The system comprises of an AdBlue tank with heater, AdBlue pump, AdBlue Injector, exhaust mixer unit, and a selective reduction catalyst. The system works by injecting an amount of AdBlue into the exhaust, this then vapourises turning into ammonia and carbon dioxide. The vapour then is mixed thoroughly with the exhaust gas in an exhaust mixer unit. The exhaust gas mixture then enters the SCR catalyst which converts the oxides of nitrogen emission’s into nitrogen and water which are harmless to the environment.

As far as the driver is concerned there is very little to do; the system is automatically controlled by the engine management system. However the AdBlue fluid does require topping up. The quantity used is about 3% of diesel consumption, the AdBlue tank under normal conditions should need only to be refilled under the vehicle service schedule, however sometimes under high load, or stop start driving conditions, this may require topping up more often.

The driver is warned that the system requires top up about 800 miles before the AdBlue tank is empty, the driver can then refill the AdBlue tank on the next visit to the fuel station. If the system is allowed to run out, the engine management system will reduce engine power for the duration of that current  journey, and after that the car will be unable to be started until the AdBlue tank is refilled.

Due to this technology only recently being fitted to cars, very few fuel stations have an AdBlue pump, or have refill bottles on the shelf, which can lead to driver frustration when an AdBlue counter is counting down, and suppliers are hard to find.

At R M Motors we stock AdBlue and if required we will refill the tank for you on a quick turnaround basis. We also can carry out repairs to the system, and if a vehicle is in for a scheduled service we would top up the system automatically.


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