The Ford Transit has a dedicated fuel port for Webasto or Eberspacher diesel or petrol (gasoline) heaters, this is introduced by the manufacturer for the addition of independent or supplementary heating.
Webasto and Eberspacher Espar heating systems are approved for installation and providing it has been installed correctly, the heater unit should not cause any 'check-engine' lights.
On older Ford Transit models the auxiliary fuel port can be located on the sender unit. On current Ford Transit models there is a dedicated fuel take-off on the tank, separate from the sender unit.
See 'figure 1' and 'figure 2' on the attached installation documentation.
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