Conversation Between marktab and signals

Hi Signals -- I'm just seeing a message from Feb 2013, and now it is Sept 2013 -- My answer is that if you reset all your codes, and then P0400 comes on again, and you have not cleaned the tube: then it is likely the EGR tube. In any case, that tube should be cleaned to allow the exhaust system to function according to design. If you clean it and the code still comes up (again, after a code reset) then you could chase other potential issues -- though most people are seeing the code disappear after this tube cleaning.

MARKTAB, I admire you for your knowledge and analytical acumen! I guess I read elsewhere "help/ info"- to test if the EGR valve or its pipe is the culprit for code P400 one could feel if the valve is sliding without binding by moving the sliding part up and down while the engine is running! Was the author kidding? Let alone while engine is running, one cannot have access to the valve even when the engine is shut off! May be I got the whole thing wrong? i would appreciate clarification. thank you very much if any one else also can give some insight into this matter.