A method for control of an activation of at least one fluid sensitive sensor (261, 262, 263, 264) of an exhaust treatment system arranged for treating an exhaust stream produced by an engine; characterized in: - determining at least one exhaust temperature T exh and at least one exhaust mass flow M ė xh for said exhaust stream; - determining if there is liquid fluid present in the exhaust stream at said at least one fluid sensitive sensor (261, 262, 263, 264), respectively, based on: - at least one elimination time function f ( T exh, M ė xh), wherein said at least one elimination time function f ( T exh, M ė xh) is based on said at least one determined exhaust temperature T exh and said at least one determined exhaust mass flow M ė xh; and - a corresponding length of at least one time period t free_of_liquid needed to eliminate a predetermined amount of liquid fluid from said exhaust stream, wherein said determining of if there is liquid fluid present in said exhaust stream at a first point in time t 1 includes: - determining a sum t sum ( t 1) of values for said at least one elimination time function f ( T exh, M ė xh) until said first point in time t 1, respectively; and - determining that said exhaust stream is free of liquid fluid at said first point in time t 1 if said at least one sum t sum ( t 1) of values is greater than at least one length of time period t free_of_liquid needed to eliminate said predetermined amount of liquid fluid from said exhaust stream; t sum ( t 1) > t free_of_liquid; and wherein the method further comprises - controlling an activation of said at least one fluid sensitive sensor (261, 262, 263, 264) based on said determining of if there is liquid fluid present in said exhaust treatment system at said at least one fluid sensitive sensor (261, 262, 263, 264). - determining at least one exhaust temperature T exh and at least one exhaust mass flow M ė xh for said exhaust stream; - determining if there is liquid fluid present in the exhaust stream at said at least one fluid sensitive sensor (261, 262, 263, 264), respectively, based on: - at least one elimination time function f ( T exh, M ė xh), wherein said at least one elimination time function f ( T exh, M ė xh) is based on said at least one determined exhaust temperature T exh and said at least one determined exhaust mass flow M ė xh; and - a corresponding length of at least one time period t free_of_liquid needed to eliminate a predetermined amount of liquid fluid from said exhaust stream, - at least one elimination time function f ( T exh, M ė xh), wherein said at least one elimination time function f ( T exh, M ė xh) is based on said at least one determined exhaust temperature T exh and said at least one determined exhaust mass flow M ė xh; and - a corresponding length of at least one time period t free_of_liquid needed to eliminate a predetermined amount of liquid fluid from said exhaust stream, - determining a sum t sum ( t 1) of values for said at least one elimination time function f ( T exh, M ė xh) until said first point in time t 1, respectively; and - determining that said exhaust stream is free of liquid fluid at said first point in time t 1 if said at least one sum t sum ( t 1) of values is greater than at least one length of time period t free_of_liquid needed to eliminate said predetermined amount of liquid fluid from said exhaust stream; t sum ( t 1) > t free_of_liquid; and wherein the method further comprises - controlling an activation of said at least one fluid sensitive sensor (261, 262, 263, 264) based on said determining of if there is liquid fluid present in said exhaust treatment system at said at least one fluid sensitive sensor (261, 262, 263, 264).