All Mercedes-Benz® Touring Coaches have a DEF or Diesel Exhaust Fluid tank capacity of 5.8 gals (22 liters).
The tank capacity can be monitored from the in-dash menu or checking the DEF container.
Like fuel consumption, DEF consumption is highly dependent upon driving style and operating conditions. DEF consumption is usually within a range of 0 and 10% of the fuel consumption. I
f necessary, DEF must be refilled in accordance with the instructions when the refill message is displayed in the instrument cluster. This may also be necessary between the scheduled maintenance.