Cadillac Repair: EGR VALVE FOR 1997 CADILLAC DEVILLE, rear valve, cadillac deville

Question
P0404 HISTORY CODE KEEPING APPEARING AFTER CLEARING.  
SHOULD I REPLACE THE EGR VALVE,IF SO, WHERE IS IT?  THE CAR RUNS GOOD BUT THE "SERVICE ENGINE SOON" LITE IS ANNOYING!  THANKS.

Answer
Hi John, It is located near the rear of the rear valve cover. It is a black round cylinder about 1 1/2" in diameter and 3" tall with a wire connector on the top. What usually happens is the valve can't open enough. You will definitely want to make sure the valve is the problem because they are at least $150. Hope that helps. Bill