Various systems and methods are described for managing ammonia storage in an SCR catalyst. In one example approach, a method comprises, in response to a vehicle-off event, injecting ammonia during a final exhaust blowdown until a predetermined value of ammonia is stored in the SCR catalyst; and in response to a subsequent vehicle-on event when an amount of ammonia stored in the SCR catalyst is less than the predetermined value, injecting ammonia until the predetermined value of ammonia is stored in the SCR catalyst.