Ford Repair: Ford Explorer 2002 trouble shooting code P1400, ford explorer 2002, vacuum leak

Question
i recently purchased this used vehicle (2002 Ford Explorer) the guy had a zapper to shut the Service engine soon light off. After a half mile it returned. I had it checked at AutoZone(parts store) and the P1400 code was given to me.I guess I should replace the EGR pressure sensor ?
also air to the dashboard vents comes out through the defroster and occasionally returns to the dashboard vents ,Is this a related issue ??
thank you for your time and answer in advance

Answer
your sensor is probably bad especially if it is aluminum they have been replaced with plastic ones-and if it is a small plastic one they give a world of trouble-

look for vacuum leak causing the vent problem especially around rear of engine on the hose going inside car.

good luck