I have a hard time believing the computer allows wider sensor parameters as mileage inceases, that would defeat the purpose of pollution control. The dealer won't fix the computer, they will however sell you a new. Usually cleaning or replacing the EGR fixes the code or changing the VSV, but a bad EGR flow sensor will also cause the problem. I'd try the dealer and see what they come up with. For computer fixes use: http://avproecm.com/index.htm

 

The internal parts of the EGR are metal, carb cleaner will not harm them. You should however keep the cleaner off the rubber diaphram that opens and closes the valve. There may also be a sensor inside that I would remove before cleaning. You'll have to use a wire brush and small scewdriver to scrap the carbon off the valve as well. I also use a hand vacuum pump to open the valve and clean the seat, just don't damage the seat as that would cause the valve to leak when closed. Soaking the valve overnight helps. Also clean the exhaust gas tube. Wear rubber gloves and dispose of used cleaner responsibly (I mix mine with used oil and take that to recycling) ascarb cleaner is toxic.

 

I tried those two and it fine to use it!