Exhaust aftertreatment system for internal combustion engines

A system for exhaust gas aftertreatment in an internal combustion engine, comprising a feed device (23) for supplying a freezable substance, in particular in the form of an aqueous urea solution, into an exhaust stream of the engine and at least one sensor array having sensors (93, 94) related to the substance state variables, such as pressure and temperature, to recognize, at least temporarily cooperating parts of the sensor arrangement with at least one fluid chamber (23) for receiving the freezable substance, characterized in that as protection against damage to the system due to volume expansion during freezing of the substance an equalizer (100, 101) acting on the respective fluid chamber (27) such that a concomitant with an increase of the fluid pressure in freezing volume expansion of the substance is compensated for within the assignable fluid space.