There are ?Refill AdBlue? warnings in the cluster. The warnings appear approximately 1,500 - 2,500 miles after the last top-off. When the AdBlue tank is refilled, the vehicle will only accept approximately 1 - 2 gallons of reductant. When checked manually, the active tank is 50% full or less and the passive tank is full. There are no reductant system fault codes stored. If any reductant system fault codes are stored, this TSB does not apply. The reducing agent transfer pump V436 may be faulty. The vehicle cannot pump AdBlue from the passive tank to the active tank. Cars in hot weather regions are more prone to this issue.
