I have a 2000 Nissan Altima. I had the EGR Valve replaced in April of 2006. This month (March 2007) my check engine light came on. After taking the car to Autozone to take advantage of their free diagnostic, I found out it was the EGR Valve code again! My question is, does the valve need to be replaced again or just cleaned? It seems odd to me that the valve would fail again less than a year later.