There is no puffing smoke with ERR. Normal Lionel TMCC smoke units have a 5Vdc power supply to drive the fan motor, with AC into the smoke unit. So it would need to me like an original Lio TMCC smoke unit or a MTH PS-1 smoke unit. Later PS-2 or Lio independent smoke unit can't stand alone connect to ERR.
Gunrunner makes the extra component to add to have puff, he also has the tach for chuff. G