Around 2009, BMW launched the "BMW EfficientDynamics" program. EfficientDynamics is the name of a strategy for BMW to reduce CO2 emissions and improve fuel efficiency all while maximizing performance. The strategy features approximately six different technologies developed by BMW to do just that.
BMW BluePerformance with AdBlue is one of the EfficientDynamics technologies, launched in 2009 in the 335d and X5 xDrive35d. BluePerformance was offered in Europe beginning in 2012, in advance of the EU6 emissions standards rolling out in 2014.
What is BMW BluePerformance?
BluePerformance is a technology found in BMW diesel engines to reduce nitrogen oxide (NOx) emissions. This technology is necessary for diesel vehicles to meet the EU6 emissions standards, as well as California emissions standards for the US.
What is AdBlue Fluid?
BluePerformance vehicles feature a second fluid tank, located either next to your fuel tank or in the engine compartment, which use AdBlue fluid.
This fluid "AdBlue" is a marketing term for Diesel Exhaust Fluid. This fluid is injected into the SCR oxidation catalyst to break down unburnt fuel into water and nitrogen. The fluid is a combination of 32.5% urea and 67.5% de-ionized water.
How does BluePerformance work?
The system uses SCR (Selective Catalytic Reduction) technology, which places an oxidation catalyst after the exhaust manifold. The oxidation catalyst features a diesel particulate filter in the same unit and a SCR catalyst with urea injection in it also.
The unit filters out small particles from the exhaust gas and injects urea, or diesel exhaust fluid, into the catalyst to effectively reduce NOx emmissions. This process generates ammonia within the SCR catalyst which converts nitric oxides in the exhaust gas into nitrogen and water vapor.
BMW's BluePerformance technology uses a two-tank system in which AdBlue fluid is injected into the active tank with a dosage pump. The active tank is connected to a passive tank which holds the AdBlue fluid.
The SCR system is ultimately controlled by the engine's ECU which controlled how much fluid is injected into the system.
How frequently do I need to add AdBlue fluid?
Because the system constantly injects fluid, the AdBlue tank depletes fluid over time and needs to be refilled.
AdBlue needs to be refilled every 15,000km or 10,000 miles on BMW's. Once you get down to either 1,600km or ~1,000 miles left of fluid, you will get a dashboard light notifying you that you need to add additional fluid. Adding fluid is as simple as pouring more fluid into the reservoir tank, located either next to your fuel tank or in your engine compartment. BMW offers free refills for the first 4 years or 50,000 miles, but DIY'ing it is super easy and can save you a trip to the dealer.
If you run low on AdBlue fluid, your BMW will enter limp mode and begin running poorly until its refilled.
Where do I add the AdBlue Fluid?
For BMW's with the tank in the engine compartment, here is a picture of the location. It is the tank with the blue cap on it:
If your AdBlue refill is located next to your fuel tank, it will look like this: