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1999 Nissan Maxima EGR valve mulfunction
Hello there,

I have a 1999 Nissan Maxima that had failed the emission inspection due to EGR malfunction. Someone told me that I just have to clean up the carbon deposit or dirt build up in the EGR valve and it should be OK. Is this true ? I'll greatly appreciate any advice or suggestion you could give me. Thanks
Hi there, the advice you got may or may not help your car pass the test. The EGR valve does exactly what the name implies. Exhaust Gas Recirculation. At operating temp the ECM opens the egr valve & runs exhaust gases back thru the intake to re burn them. Quite often carbon build up can either hang the valve closed, or slightly open. Either way it will affect emissions, & sometimes engine performance. Remove the valve & clean the inside with carb cleaner & small pick or screwdriver. Make sure the rod inside the valve can move freely & seat completely. Reinstall with a new gasket & hopefully problem solved. If not post back with more details & we'll go further. DD
If it ain't broke go faster!
Yes, DD's answer. Give us more details on the emission test: idle-only or loaded (dynamometer) test, and test results for HC, CO, NOx, and CO2 for the whole test if you have all of those values. Sometimes you only get HC and CO numbers, but give us what you have. If the test was run on a dynamometer at more than one speed, give us all the test results and all the test limits as well.

After removing my '99 Maxima EGR Valve, saw that it had a black sooty wet film on its internal ports, but not clogged. The Plunger appeared to work when I took apart the Stainless Steel Motor which was fastened with 3 #4 internal hex head bolts. Cleaned with a rag as best I could, then re-installed. The Check Engine Light went out, but came back on in about 20 minutes of driving. This was a little bit of a Struggle to remove. I needed a 30mm wrench to loosen the Hex Nut connecting the exhaust gas tube from the EGR valve to the Manifold. Tried to use an Open End Wrench, but the longer part of the wrench rested against the Brake lines coming off the Master Cylinder. So I had to order a 1 & 3/16"(30mm equivalent) 12pt.Crowfoot Flare End Wrench from Snap-On to loosen it. Didn't take any of the tubes off. Was surprised to see there were 2 small Antifreeze lines attached to the EGR Valve, is this a method of cooling it assuming it gets very hot? Any other suggestions on the repair or cleaning?
Well, I am also looking for auto repair reviews as it is very necessary to have before going to repair the vehicle. As this Nissan Maxima EGR valve malfunction is there and it is only repaired by some of the good mechanic who have much experience in automobile field.

I would recommend you to clean up the carbon deposit or the dirt build up in the EGR valve and it should be ok. Though going by what DD has to say is also correct which will be great.
egr cooler 6.0

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