Hi everybody,

I have done my best to read the rules and make sure I am posting this in the right place, but if I am not, or otherwise doing anything wrong, please let me know.

A couple years ago I bought my first car, a 2008 Mercedes-Benz E320 Bluetec. At the time I didn't know a lot about cars beyond how to operate one, but I really liked this car and how it drove. I still love it, but what I didn't love were the repair costs that I would get at various mechanics. In an effort to save money, I have been trying to learn more about cars in general, and trying to see what I can do to maintain and fix my E320 by myself.

Recently, the check engine light came on and gave me the codes P0402 and P0472. I haven't done as much research into the second code, but I understand the first code relates to the EGR system, and reading various forum posts and articles, it seems that sometimes these issues can be fixed by cleaning the carbon buildup on the EGR valve. However, I spoke to somebody at a parts store recently, and he didn't think the buildup would be in the valve, but rather deeper in the system, in a much harder spot to access. He suggested I use seafoam in the air intake to try and clean the system.

I wanted to make this post here to get feedback from people who know and love similar cars to make sure I get the best info possible on this. What would you guys suggest doing? Also, once I do something to attempt to fix this, how do I get the system to actually update and turn the CEL off, and ultimately how do I know for sure that I have fixed it?

I really love this car and want to be able to work on it and understand it, even if everybody tells me that Mercedes are very difficult. (I also haven't been able to find the service manuals that seem to be very helpful when doing anything on a car).

Any other general advice about this car and best practices is very welcome.

Thank you guys in advance!