Ford Repair: EGR Sensor, advance auto parts, vacuum leaks

Question
I have a 96 Ford Explorer 5.0 Liter, V-8, AWD, Eddie Bauer, August 1996 production line

Problem:
I am losing A LOT of gas everyday. On Monday morning August 8th, I started out with a full fuel tank (20 gallons to empty). I went to work and traveled approx. 5 miles. I parked my car and when I went to lunch I noticed that I had 12 gallons to empty. I do not smell gas in my car, and the check engine light came on and stayed on all day Monday. That evening it turned off, but I am still losing a lot of gas, which is getting expensive to keep filling up.

I had a Texaco Oil and Lube do a brief diagnostic test (they only hooked the computer up to it) and it read EGR Flow...something something and it was a code 0401.

I bought two different types of sensors at Advance Auto Parts and I need to know which one I should have NAPA put in for me. Also, I need to know if it's true that (what the guy at NAPA told me) if I replace the sensor then I have to replace the EGR Valve also and have the system cleaned out. I DO NOT want to keep putting money into a car that I am going to sell within the year.

What is wrong with my car?

Best Regards,

Lauren

Answer
Hello and thanks for the question...I'll try to help.
The EGR isn't going to give you a loss of gas problem. I would get it diagnosed first. Getting codes is only an indication of where to start the diagnostic routine to isolate the fault.
I would take a look at other things for the fuel loss:
1. Vacuum leaks
2. Fuel pressure
3. Over all tune up condition of the engine

Erik