Nissan Repair: egr system, nissan altima, computer readout

Question
i have a 95 nissan altima the check engine lite came on. the computer readout says the knock sensor and the egr system is the problem. what is the egr system and where can i go to see it.

Answer
Replace the knock sensor as these are a known problem.  The EGR system is comprised of an Exhaust Recurculation Valve and a sensor that reads what it is doing.  If the valve gets stuck it will set the MIL and you say it has.  I would first replace the knock sensor and reset the light and see if that corrects the problem.  The EGR valve is not too difficult to replace but it will cost about $100 to replace.