How to Clean your EGR Valve on your Mazdaspeed 3/6 or CX-7 to fix the P0401 CEL Code

Raider

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Got a P0401? This is for you. Your EGR is stuck. Colder weather will create this more often too. light will go off after 4 driving cycles, but return if still stuck. This is for people who want to retain the EGR. You can block it off and clear the CEL through AccessPort if you want. I performed this cleaning 6 years ago. A couple years later I got the code again. I read about Chevron Techron Complete Fuel System Cleaner (big bottle) from an auto parts store helped many. Well I went and used it on a tank. 200 miles later, I think 8 driving cycles, and light went off and stayed off for a year. Repeated annually. SO this may be an option if not totally caked. Eventually I got an Accessport and blocked the EGR.

I got a P0401 CEL at 51K miles on my 2007 Speed 3 the other day after 2 or 3 days of slow starts, where it would crank a while before firing up. Guy at Advanced who read the code said EGR was clogged, a $430 part from the dealer. Having owned a Protege 5, I knew what a stuck EGR was like, and how it can be cleaned, but no how-to posted yet for the Speed3 apparently. I read a few threads online, and here especially, so I am posting here first to share. This is how I did it. Feel free to do it differently if you feel like it. This is probably not the only way to do it. It is just how I did it. Don't like it? Well, sorry I guess. A 10 and 8mm deep and shallow socket, pliers, a 22mm wrench, flat blade and Philips screwdrivers, Brake Parts cleaner, and some coolant will be needed. Oh,and a person with skinny fingers.

1st, it is not that hard to do if you know a little bit on working on our cars already.

1st, where is the EGR. It is here:
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Now what to do. To start, remove your OEM TMIC, battery and battery box. Also remove your turbo inlet pipe. loosen the top on the coolant overflow tank. Put a rag in the turbo.

The EGR is the silver thing with the black plastic on top. The pipe with 2 bolts coming out to the left of it is the EGR pipe.
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Remove the 2 bolts holding the EGR on, and pull it out. Here is the EGR with the gasket on it. You cannot see it, but there is carbon inside, Nasty, but comes out easy.
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Now go up tho the front to the throttle body. You may make a mess if you have not already removed the coolant lines from the throttle body like I did. If you did not, do it now.
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There is a hose coming out of the back of the EGR, held on with a clamp. Pull the clamp back, disconnect the hose from the EGR, and let the coolant drain. You will lose a quart or so, the overflow will be empty.
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Remove the 2 bolts holding the EGR on, and pull it out. Here is the EGR with the gasket on it. You cannot see it, but there is carbon inside, Nasty, but comes out easy.
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Admire the nice pile of carbon in front of the pipe.
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Feel free to blow compressed air through the pipe while it is removed. If clogged, use a coat hanger or something, and get out as much as you can. You might need to take it to a mechanic to get it dipped in parts cleaner if you do not have it.

Skipped pics, but remove the 4 screws holding the plastic top of the EGR valve. Don't strip or break them. They are as a strong as Dollar Tree trash bags.

There is a plunger. It is stuck. spray with brake cleaner on the holes, until clean, Scrape out carbon if needed.

Then reinstall everything.
The end.
 

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Nice - also the reason I don't suggest people simply unplug the EGR and wipe the code for a "delete". If it's crudded up, the default closed position may not be fully closed.
 
This is true. not hard to remove with multiple vendors offering EGR delete options for those who have an Accessport.
 
I like the EGR delete, not the pipe but the full delete. Great write up (again) Eric!
 
Just carb cleaner. B12 will work too.
 
Great write up! When in doubt just do the full EGR deleted (pump and pipe), assuming you can get away with it for emissions, I've installed both JBR and CPE full kits and personally I like the install on the JBR kits, (bolt head sizes slightly different enough to make the install easier). Just my 2 cents

Edit: but for those who cant do the delete for whatever reason this is an excellent how 2
 
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deletion is always best, but for those who don't or cannot, this is how to.
 
WA state doesn't require emissions testing for cars 2009 and newer... so I just missed it. So my EGR is just unplugged because every 2 years I have to do an emissions test and will fail if any EGR-related code is thrown. So that sucks, I want this thing gone and reinstalling it every 2 years would be a RPITA.

There was talk previously about searching for a way to trick the electronics system into thinking the EGR is operating normally with a clever arrangement of resistors (to avoid "P0403 EGR circuit malfunction" from unplugging) but you would also need to fool whatever sensor measures the flow through the pipe (P0401 EGR flow insufficient) so I've yet to see a permanent solution to both after removing.

The other best option was from @MATT DAMOND I believe where he drilled a tiny hole in a nut or something and jammed into his EGR pipe, which allowed a tiny amount of air (enough to avoid the codes) but not enough to gunk up his IM from the exhaust gasses. Before and after driving for a while pics were convincing.
 
Yay, a revive!

Appreciate this post @Raider - P0401 just popped up for me at 68k on my 08.5. Gonna try the Chevron juice first, as my car is starting and idling fine.

Figured its worth 13 bucks before the next step of disassembly and cleaning.
 
Techron didn't do shit for me. My CEL goes away after a full tank of gas and a number of starts but comes back on when my tank is low ¯\_(?)_/¯

Sent from my LG-H918 using Tapatalk
 
Hi all, I'm n the middle of this job on my 2008 (59k miles). I can't find torque specs for the EGR system or throttle body on any of the forums. Does anyone know what to torque everything to?
 
Great write up, handy for everyone who still sporting there EGR
 
Just saved my day- took about 5 hours with my noob knowledge (stomach flu doesn't help,) but hooooooooly damn that thing was carbon clogged. Maybe now I'll finally get to pass emissions.
 
Hi:
First post... My son just bought his first car (2006 Mazda 3 S trim with the 2.3L motor (Canada)). It's a great car, but it's throwing the following:
P-0030 followed by
0131
0030 (again)
0401
my car nut work colleague thinks they might be related, and suggested cleaning the EGR valve first (after finding this article), and see what happens. Any advice would be greatly appreciated, to avoid struggling with that EGR valve if I don't have to. Thanks!
 
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