HI,
I have a98 E320 with 116k,check engine light on.Scaner says "P0400 Exhaust gas recirulation flow malfunction.Replaced the gas cap reset the code,but it came back on 12 miles later.What else should I look at?Thanks for any help.Rob

Read through all of these post.............and call me in 2 weeks.

http://www.peachparts.com/shopforum/search.php?searchid=254434

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2007 C 230 Sport.

On the M112/113 engines that code normally means the EGR tube is plugged OR that the valve isn't functioning properly. AT dealer we either replace the valve and clean the tube OR replace the valve & the tube!

Normal list for the parts is under $200 & take about 45-60 minutes.

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MB DOC, Thanks I will try cleaning or replacing the egr and tube.

Sounds like you're well on your way to rectify this little annoyance.
Btw., received your P/N but it looks like you're in good hands right here.

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2007 C 230 Sport.

I have a 2000 ML320 and getting a PO400 code. Removed the tube and very little carbon so cleaned it and checked the EGR valve and attached solenoid valve and both functioned perfectly. Replaced the vacuum tubes on the valve and the one going to the intake, reset the codes and after 30 miles the light is back on. Is there anything else that is in the EGR circuit that might be causing this problem. I am thinking whatever controls the solenoid valve on the EGR. If so where would that be located? One last thing, if the codes are reset with a OBDII and cleared does that reset everything or is there additional procedures to completely eliminate the trouble codes?