2001 mustang v6 3.8 shows code 401 with OBD11 reader have put out lite but keeps coming back on faulty sensor?

This only started happening after car had been parked for three weeks the generic code po 401 says exhaust gas recirculation flow insufficient detected. mustang v6 with a 3.8 I am using a digital obd11 reader|||some of the things u need to check when this code comes up is ur EGR vavle, EGR sensor, vaccum lines, and PCM and any lines off the EGR system|||Sounds like the DPFE sensor. If the EGR ports are not clogged, then it is probably the sensor. They are known to fail.|||DPFE sensor known ford problem. well not a " Ford" problem but with the part manufacturer. .. all models of ford have the recall or the TSB on this concern. Call your local ford store with your vehicles VIN number and ask the serv dept to run an OASIS on your car to see if its under the TSB or the recall.