Check engine light came on. EGR valve replaced. After a few months check engine light came back on. Mechanic said EGR hose was now clogged. Could unclog hose but the heads may still be clogged and cause the check engine light to come back on. Won't pass inspection in current condition.
My car has ignition problem (my check engine flashed urgently), I first thought it was some spark plugs, so I tell a mechanician in a auto repair garage. He found some codes on his machine, whose ignition problem. He tried to find where the problem was located, he checked my spark plugs (visual check of two spark plugs) and said they were used but not the source of the problem. They said my E.G.R valve was completely opened due to fouling in my mechanic and they partially fixed the problem. They mostly recommend me to change the EGR valve. I asked an other mechanician to check, and he said that the problem must be the spark plugs, but E.G.R valve problems are possible too. Today, the mechanician is working on my car, he change my EGR and all spark plugs, I'm hoping the problem will be solved.
Check Engine Light ("CEL") came on and codes appeared for Exhaust Gas Recirculation (EGR) Valve and also Knock Sensor. First shop wanted over $1000 to repair these. Took it to a dealer, which offered to do it for $500, saying it was just carbon buildup in the EGR ports, probably not actually a bad EGR Valve. And Knock Sensor code was just a side-effect. Finally got it cleaned for $400 by another Nissan dealer in TN.