Method for predicting urea crystal build-up in an engine system when operating according to an intended drive cycle, wherein the engine system comprises an internal combustion engine and an exhaust gas aftertreatment system provided with an urea solution dosage arrangement, the method comprising: - providing data representing engine operational conditions for the internal combustion engine during the intended drive cycle, wherein the data comprises values for at least engine speed and engine torque distributed over a time period representing the intended drive cycle; - determining values and time variation for at least one exhaust parameter during the time period of the intended drive cycle when the engine system is operated according to the engine operational condition data by importing the speed and torque engine operational data into an engine system calculation model that is set to simulate the engine system; - providing a reference relation between values and time variation for the at least one exhaust parameter and an expected urea crystal build-up in the engine system when operating the engine system at different engine operational conditions, - predicting urea crystal build-up in the engine system when operating according to the intended drive cycle by comparing the determined values and time variation for the at least one exhaust parameter with the reference relation; wherein the exhaust parameter is at least one of: an exhaust gas temperature, an exhaust gas mass flow rate, and/or an exhaust gas energy ratio reflecting an energy content of the exhaust gas in relation to the energy required to evaporate dosed urea solution. wherein the engine system comprises an internal combustion engine and an exhaust gas aftertreatment system provided with an urea solution dosage arrangement, the method comprising: - providing data representing engine operational conditions for the internal combustion engine during the intended drive cycle, wherein the data comprises values for at least engine speed and engine torque distributed over a time period representing the intended drive cycle; - determining values and time variation for at least one exhaust parameter during the time period of the intended drive cycle when the engine system is operated according to the engine operational condition data by importing the speed and torque engine operational data into an engine system calculation model that is set to simulate the engine system; - providing a reference relation between values and time variation for the at least one exhaust parameter and an expected urea crystal build-up in the engine system when operating the engine system at different engine operational conditions, - predicting urea crystal build-up in the engine system when operating according to the intended drive cycle by comparing the determined values and time variation for the at least one exhaust parameter with the reference relation; - providing data representing engine operational conditions for the internal combustion engine during the intended drive cycle, wherein the data comprises values for at least engine speed and engine torque distributed over a time period representing the intended drive cycle; - determining values and time variation for at least one exhaust parameter during the time period of the intended drive cycle when the engine system is operated according to the engine operational condition data by importing the speed and torque engine operational data into an engine system calculation model that is set to simulate the engine system; - providing a reference relation between values and time variation for the at least one exhaust parameter and an expected urea crystal build-up in the engine system when operating the engine system at different engine operational conditions, - predicting urea crystal build-up in the engine system when operating according to the intended drive cycle by comparing the determined values and time variation for the at least one exhaust parameter with the reference relation; wherein the exhaust parameter is at least one of: an exhaust gas temperature, an exhaust gas mass flow rate, and/or an exhaust gas energy ratio reflecting an energy content of the exhaust gas in relation to the energy required to evaporate dosed urea solution.