Unclogging group for unclogging a filter of a pumping group for pumping diesel to an internal combustion engine, the unclogging group (1) comprising: —a metering unit (2) supplied by diesel leaving a low pressure pump and configured for feeding in a controlled manner the diesel to a high pressure pump; the metering unit (2) comprising an electromagnetic head (4) provided with a coil (6) and a control valve (5) for controlling the diesel flow; —a filter (30) associated with the control valve (5); —a temperature sensor (34) for measuring the ambient temperature; —a control unit (31) coupled at one side to the temperature sensor (34) and at another side to the coil (6); wherein the control unit (31) is configured so that once it has received the starting input of the pumping group it compares the temperature measured by the temperature sensor (34) with a threshold value, and if the temperature measured by the temperature sensor (34) is less than the threshold value the control unit (31) commands a delay of the starting of the pumping group of a period wherein the control unit (31) supplies electrical current to the coil (6).