tworock - parts prices - WIX fuel filter without sensor ca. $30 NAPA; sensor ca. $20 dealer or mail order; 2nd gen fuel head which comes with new fuel filter AND sensor installed plus the required wiring/heater plug pigtail ca. $125 shipped if you shop around. See
http://www.greendieselengineering.com/f ... st/76.page on why you need the 2n gen head and how to tell if you already have it.
If you have a 1s gen head pull the heater plug and check for a diesel leak. If present the dealer needs to warranty replace the head assembly and pigtail or replace it under TSB 18-011-09 APR 09.
Recommendations - if you have a 1st gen head either DYI the 2n gen head or have the dealer do it. If you do the latter and they don't warranty or TSB it be sure you only get charged for the head unit and wiring pigtail NO separate fuel filter or sensor charge as they both come with the head unit. If you already have the 2n gen head I'd either DYI a fuel filter change or have the dealer do it WITHOUT replacing the senor. My personal bet is, absent the wiring issue ATXKJ mentions, the sensor is just fine but your old filter has trapped water. If that's the case replacing it with a new filter should make the warning light go out. If not then and only then you might have a bad sensor and replacing that can be done with the new filter on the vehicle.