Engine=exhaust pollution=reducing system with catalytic unit

摘要

A device heats the catalytic unit in the exhaust and the engine coolant independently of the engine. On starting up, temperatures of the coolant (TKW-ST) and intake air (TAN-ST) are detected (Stages S1.S2). The temperature of the coolant is then compared with a first upper threshold value (GW1) (state 3). If this value is not reached, both values are checked for fulfilment of a further condition (Stage S4,S5) which is characteristic of completed heating of the coolant by the independent heater. When these two further conditions are fulfilled, the heating of the catalytic unit is cut in.