The "Service Engine Soon" light lits up on the dashboard of my 1997 Nissan Maxima. I went to O'Reily and borrowed their AutoXray ODBII Reader. The reader returned trouble code P0400 "Exhaust Gas Recirculation Flow Malfunction". I believe I either have to clean the EGR valve with carbon cleaner or replace the EGR valve all together. I am not sure which one is a better idea. In addition, I am not sure where is the EGR valve located and whether it can be replaced easily. Please advise. Thanks.

P.S. I had reset the ECU several times and everytime, it returned with the same trouble code after driving for about 45 miles. I think I have to do something about it before I take the car for state inspection. Thanks.

Best Regards,
William

 

William,
first thing, does you car run the same as it used to? when the egr is bad the car will not hold an idle and will always run rich. if the car still seems to run alright then you should be able to get away with just cleaning it. but just because you got the egr code does not mean the egr is the problem. There could be another reason your geting the egr code. I would try cleaning the egr and if you still get the code, you might want to take is somewhere to get it looked at. if you need to locate is i think it is best to just buy the hanes manual. i could try to discribe it to you but the manual is really what you need.
Let me know how it turns out.

 

more than likely the steel tube from your intake to your EGR is comepletely plugged with carbon your EGR valve is ok may need a little cleaning. its about a 2 hr job to clean the tube out (its not the big tube to your exh. manifold) or the vacuum line from the BPT valve to the source vacuum steel line has deteriorated and has a hole in it. Trust me this will fix your problem

 

jedi, do you live in PA? or some other rough emissions state?