Ford Repair: Check engine light, ford exp, egr system

Question
I have a 97 Ford Exp. 6 Cyl..  The check engine light came on.  No difference in the ride.  I diconnected the ground to reset the comp the light stayed on for about 3 days and then came back on.  Went to auto zone - the code came up P0401.  However there were a few things that could be wrong. Could you possibly advise me what would be the most logical problem? I have seen in previous questions the adice was to replace the EGR valve.  Any advice would be of great interest.
Thank you for your time and advice.

Jeri  

Answer
The Check Engine Light comes on when there is a problem in the vehicle's emissions system. It is safe to drive a vehicle with the Check Engine Light on, unless it is flashing.  The Diagnostic Trouble Code (DTC) only indicates which circuit the computer sees a problem in, it doesn't always mean that the sensor is bad.  In your case, the P0401 code is common, it translates to "Low EGR system flow".  Since the EGR valve almost never needs to be replaced, the EGR Pressure sensor (DPFE Sensor) is probably bad.

I hope this helps,
Dave