Yesterday I had my codes pulled and 3 came up, (P0301, P0300, P0400). I replaced the plugs and reattached a vacume line that was off, from the EGR valve. I reset the computer and then last night the engine light came on again. When I pulled the codes again the P0400 code came up again. (EGR flow malfunction)
I was reading another post where the tube to the EGR valve was clogged. Is this something that is common on all models, or is it just that time for my year of mercedes to replace the EGR valve?
I was hoping that the vacume line that was disconected would solve my problem, but it only took about 5 miles of driving before the engine light came back on.

Our valued member Arthur Dalton ( affectionately refered to here as " The Old Geezer " ),has given the test procedure many times.
With the engine idling, apply vacuum to the EGR valve.
If the engine stumbles or dies, the EGR is working.
If no reaction, you could have an inoperative EGR Switchover Valve, or possibly a plugged tube.

Btw. It's not considered good manners to post the same problem twice!

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2007 C 230 Sport.