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P0401: Egr Insufficient Flow

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dignosing this problem right now on the 99 camry 2.2L inline 4cyl


the EGR valve seems to be working (runs rough when apply vacuum to the 1 port) but the vacuum doesnt hold like it says it should (leak in a diaphram plunger internally???) and the ... the ... the thing that sits right next to the EGR valve ... name is escaping me right now ..., that seems to have air flowing normally through it in one direction anyway. I didnt spend a lot of time trying to determine if it was resisting flow at higher RPMs.


New EGR valve is EXPENSIVE. Any shade-tree fix methods?


Two things to note:

-The problem progressively got worse (assumption from the fact that the CEL would come on and go off at longer and longer intervals until now it just remains on all the time).

-One of the vacuum lines in the area of the EGR valve (not sure which one) was completely plugged with carbon/soot dust. I'm in the process of replacing all of them but didnt have enough tubing ... gotta pick some more up.

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Cleaning the EGR valve / tubing would be my first crack at it. Any vacuum leaks from hardened rubber hoses or oil soaked, otherwise damaged hoses would be my next plan of action. Some shops like doing a top-end clean to attack the carbon buildup from another avenue. You will have to open the valve 100% to prevent it from loading up with carbon chunks when you do that. Might be able to get away with a distilled water or Seafoam or similar treatment - basically steam blow the carbon out of there.


Our own Carmy did that - cleaning helped, but the problem always came back. Eventually had to replace it, as the bottom tube portion got chewed up - even with a parts discount, I believe we still paid about $200 for the just the EGR valve. You have to double check the vacuum modulator, hoses, VSV valve, etc. Also had to assume the EGR gas temp sensor was OK - some cars, you have to replace them both - like Ford = $$$.

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