dtate Posted March 22, 2009 Share Posted March 22, 2009 Hi all, Last week my daughter's 97 OBS check engine light came on and she had the folks at Autozone read the code for her. It was PO400 emission air recirclation fault. They told her that mosture in the system may have caused the code & to try some gas treatment in the fuel & see if that will keep the code from coming back. I have looked at the threads concerning this code & it looks like the problem could be in the vacumn hoses or the EGR valve. Since having the code read, she has driven the car aout 100 miles without a repeat of the code. I have visually inspected the vacumn hoses & they look Okay. Two questions, does the Autozone idea of fuel tratment seem like a likely fix, or is this a good sign that I will be needing to have a pro look at the hoses & check out the EGR valve? Any comments & suggestion are most welcomed! Thanks dtate Link to comment Share on other sites More sharing options...
nipper Posted March 22, 2009 Share Posted March 22, 2009 Its not a horrible idea, but if you are using fuel with ethanol it is already in there. It is also possible that the additive may help dry out the carbon around the EGR valve seat. It can be that the EGR valve is sticking or failing. I would test it for function (rev the engine and watch the valve move). Check the vacume line. It may have been a one time thing where moisture caused the valve to stick. if it happens again clean or replace the EGR valve. Dump a can of Techron in the car twice a year. that may help. nipper Link to comment Share on other sites More sharing options...
dtate Posted March 22, 2009 Author Share Posted March 22, 2009 Okay, so I quess it is reassuring to know that the suggestion was not off base. So, while revving the engine I should be able to hear a clicking sound as the EGR valve engauges. I may give that a try. The car is driven about 250 miles or so a week, she is student teaching, so she will have run the treated batch of gas through the car this week. When she comes home next weekend, I will see if I can hear the EGR valve. If she has no problem with it this week, should I go ahead and disconnect the battery to reset the CPU and clear the codes, or not worry about it? Link to comment Share on other sites More sharing options...
nipper Posted March 22, 2009 Share Posted March 22, 2009 EGR valve is not electronic (there still are mechanical valves). You should be able to see it operate just by reving the engine. It is operated with a vacume diaphram. Dont use drygas, use Techron. If the CEL doesnt come back on again, just leave it be, the code will or already has cleared itself. nipper Link to comment Share on other sites More sharing options...
Bigbusa Posted March 23, 2009 Share Posted March 23, 2009 I had the same code on my 96 obs. I replaced many things but it eventually turned out to be a simple, easily fixed, problem... the EGR valve was slightly dirty. Take it out, wash it as best you can and wire brush the inside of it and you'll probably be all set. Link to comment Share on other sites More sharing options...
Hondasucks Posted March 23, 2009 Share Posted March 23, 2009 Try opening the EGR valve manually with the engine running (lift up the diaphragm with your finger) this should cause the engine to stumble and die, if it does not stumble and die, or if it just starts running a little rougher but doesn't die, you probably have a dirty valve and/or EGR passage, which can be cleaned with a brush and some carburetor cleaner. If it does stumble and die, your EGR flow is okay, but you might have a leaky diaphragm in the EGR valve. Take the hose off of the valve, and apply suction to the vacuum port on the valve, the valve should open and stay there, if it does not, chances are the diaphragm is leaking, and you will need to replace the EGR valve. Link to comment Share on other sites More sharing options...
dtate Posted March 23, 2009 Author Share Posted March 23, 2009 So far it sounds like it maybe easily checked out. When she is back home, I will take a look at the valve. Thanks for the suggestions & anyother comments will be appreciated! Link to comment Share on other sites More sharing options...
idosubaru Posted March 23, 2009 Share Posted March 23, 2009 On the passengers side of the engine bay is a vacuum line running from the passengers strut tower to the engine bay that has a small (quarter size in diameter), round filter on it. they are $7 from Subaru. replace that first. next step i'd clean the EGR valve. often they just need cleaned. they have a gasket so if you remove it you may need a new gasket. good luck! Link to comment Share on other sites More sharing options...
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