Method and contol system for control of dosage of a reducing agent

A method, a system, a computer program and a computer-readable medium for control of dosage of a reducing agent into an exhaust stream from an engine are disclosed. The method method includes:- determining at least one sensor signal Sfrom at least one nitrogen oxides NOsensor arranged downstream of at least one of the one or more reduction catalysts as at least one sensor correction value S, respectively, if:- the engine revolves without fuel supply;- an exhaust mass flow Mis greater than an exhaust mass flow threshold MM>M; and- the at least one sensor signal Shas had a value smaller than a sensor signal threshold SS