Got car back last Thursday (04/02) with diagnosis of moisture in fuel. Tech said he did not know why this was triggered and there was no way to test as they do not have a method to test for water in diesel fuel. Said car was running fine. Left next day on 250 mile trip with no problems whatsoever. The next day after I filled up with diesel to return home, warning light came on 30 minutes later. I am purchasing diesel at the same places I did for the first 6,000 miles of the car. Anyone know of a test for water in diesel and what might be triggering this warning?