PO400 engine code

rgeros · #1 (**permalink**) 02-10-2009, 06:32 PM

quick question, I have a 1996 altima in the shop with a PO400 code and the shop states its due to a blocked high temp hose, and wnat to charge me 3 hours to unclog it. This sounds like its an easy job to just clean out a hose. Does anyone know where exactly this hose is located and is this easy to do?

Thanks,

9594Altima · #2 (**permalink**) 02-10-2009, 06:52 PM

The code is EGR flow malfunction which There are 4 "metal" tubes coming out of the EGR itself... Cleaning them all would be near impossible. Unless you can lay across your engine, or some how contort yourself under the damn thing... The biggest problem I ran into was getting to everything. I would recomend checking/replacing the selenoid. If you get vacum there before that, Id say thats it, seldom will a vacum hose have 0 vacum, you should feel it at the EGR. Even a little... If you reach around the top "cone" of the egr you will feel a rubber/plastic part... This moves up and down with the RPM, at about 2k you should feel it shoot up fast, and thus open the valve. When the engine slows down you can feel it sit back down, check for debris around the lip of that rubber gasket.

rgeros · #3 (**permalink**) 02-10-2009, 07:07 PM

Thanks 9594Altima, I did check the egr operation myself before I dropped the car off and it seamed to be operating properly. The car does idle a littel rough which makes me think its a vacume problem, but dont know where.

9594Altima · #4 (**permalink**) 02-10-2009, 08:00 PM

sorry couldnt be more help

sstupid · #5 (**permalink**) 02-10-2009, 09:18 PM

There is a rubber vac hose going to your EGR diaphragm. Check to see if there are any holes or cracks in it.

Remove your EGR sensor and see if it's caked with carbon. I'm not sure that that would cause the error you're having, but it never hurts to clean it anyway.

Lastly, you can remove your EGR valve and suck on the diaphragm to see if the shutter is opening and closing.