The auxiliary heater does not work if the fuel level is low. If the low fuel warning indicstor is on the dash, the control module inhibits the auxiliary heater. The pick up for the heater is sat just as low as the main pick up. The quickest and easiest way to stop the smoke is to remove the fuse for the auxiliary heater control module. It is in the engine bay fuse box. 3rd fuse from the right, top row. 20 amp. Remove this and no more smoke. This has no affect to the engine. The eml coming on will not of been related to the auxiliary heater. Maybe just pulled a little air in if fuel level was very low.