I had this same issue with my 98 ficht 150. I drained the tank, cleared fuel lines, replaced fuel/water separator, fuel filter/sensor and even ran it from a brand new aux tank. I ended up sending it to DFI to be rebuilt for $600, repairs and shipping were fast. According to DFI and seahorse (on another forum he was helping me) if you disconnect the sensor and it still throws the code then the issue is with the ECU. I chose not to ignore it for fear that I would overlook a legit code and had it rebuilt. its up to you