An exhaust gas treatment system for an internal combustion engine, the system comprising: an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine; a diesel particulate filter, DPF, element positioned in the exhaust gas pathway, the DPF element configured to capture particulate matter from the exhaust gas; a regenerator operable to increase the temperature of the exhaust gas that passes through the DPF element; and characterized by a controller configured to selectively operate the exhaust gas treatment system in a first mode in which the regenerator is inactive such that a temperature of the exhaust gas is within a first range, a second mode in which the regenerator is activated to increase the temperature of the exhaust gas to a first target temperature beyond the first range, the second mode being a passive regeneration mode, a third mode in which the regenerator is activated to increase the temperature of the exhaust gas to a second target temperature greater than the first target temperature, the third mode being an active regeneration mode, and a fourth mode in which the regenerator is activated to decrease the temperature of the exhaust gas to the first target temperature, the fourth mode being a passive regeneration mode, wherein the controller is further configured to determine (S 120) whether the regeneration is complete, and if the regeneration is not complete to repeat the third and fourth modes. an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine; a diesel particulate filter, DPF, element positioned in the exhaust gas pathway, the DPF element configured to capture particulate matter from the exhaust gas; a regenerator operable to increase the temperature of the exhaust gas that passes through the DPF element; and characterized by a controller configured to selectively operate the exhaust gas treatment system in a first mode in which the regenerator is inactive such that a temperature of the exhaust gas is within a first range, a second mode in which the regenerator is activated to increase the temperature of the exhaust gas to a first target temperature beyond the first range, the second mode being a passive regeneration mode, a third mode in which the regenerator is activated to increase the temperature of the exhaust gas to a second target temperature greater than the first target temperature, the third mode being an active regeneration mode, and a fourth mode in which the regenerator is activated to decrease the temperature of the exhaust gas to the first target temperature, the fourth mode a first mode in which the regenerator is inactive such that a temperature of the exhaust gas is within a first range, a second mode in which the regenerator is activated to increase the temperature of the exhaust gas to a first target temperature beyond the first range, the second mode being a passive regeneration mode, a third mode in which the regenerator is activated to increase the temperature of the exhaust gas to a second target temperature greater than the first target temperature, the third mode being an active regeneration mode, and a fourth mode in which the regenerator is activated to decrease the temperature of the exhaust gas to the first target temperature, the fourth mode being a passive regeneration mode, wherein the controller is further configured to determine (S 120) whether the regeneration is complete, and if the regeneration is not complete to repeat the third and fourth modes.