The volume of the tank on your Sprinter is 18L.
The first warning is given at 1500 miles. When the remaining distance is less than 600 miles, the second warning is given. When the remaining distance is less than 375 miles, the engine’s power output drops by 25%. When the remaining distance is less than 90 miles, your maximum speed is limited to 13 miles/hour.
As soon as you see the AdBlue® warning light, you should refill your AdBlue® tank so as to be able to restart the engine. If you do not fill up with AdBlue®, you will not be able to restart your car. The message "Add AdBlue®, Engine start impossible” is lit, informing you that you need to fill the AdBlue® storage tank. If your tank is empty, pour at least 3.5L into the tank, turn the key in the ignition for about 60 seconds and then start the engine.
This information can vary on some vehicles of the same model in relation to the options chosen by the manufacturer.