Ha! The EGR port is completely plugged. That could result in "insufficient flow."

2001 Honda Odyssey EGR Port Fix for P0401 Code

Our 2001 Honda Odyssey needs to pass Oregon’s DEQ to get updated license tags. Unfortunately, the check engine light wouldn’t stay off and it had code P0401 — Exhaust Gas Recirculation, Flow Insufficient.

After paying for a new EGR valve and catalytic converter (I’m not complaining, I don’t think we’ve had problems with either of these for over 220,000 miles), trying more expensive gas and gas cleaner additives, the code still showed up. Time to take matters into my own hands.

But first, I needed some information. Searching YouTube resulted in the following video:

I also found Honda’s service bulletin 00-009 which has been superseded by Honda service bulletin 05-026.

Ordinarily, any instructions that tell me to remove big hunks of metal from my car’s engine, do something to them, and then put them back on would scare me off. However, having to pay someone more money to fix my car and/or not getting my car fixed in time before the trip permit expired scared me more.

I forged ahead, basically following the method from the YouTube video, informed by the steps of the service bulletin and the torque specs and reassembly instructions from an online Chilton’s manual.

Any time I attempt a fix, I take lots of pictures and take notes so I can put it back together. Some of the pictures are attached below.

I hope to be able to update this with a picture of my OBD II checker showing no errors after a complete drive cycle.

Wish me luck!

Update: I should “clear the air” a little about where I cleaned the intake manifold. I used the carburetor cleaner in the garage with the door open, not in the kitchen sink. You don’t want to use that stuff in an enclosed space. I used the kitchen sink to rinse out the manifold when I was done with the carburetor cleaner.

Update 2: The fix worked! Woo hoo!

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Brent Logan

Engineer. Lawyer. WordPress geek. Bicycle commuter. Blood donor. Snapshooter extraordinaire.

10 thoughts on “2001 Honda Odyssey EGR Port Fix for P0401 Code”

  1. Great post Brent. I’m hoping to hear good news from your test. It looks like you did indeed find the problem. I loved the egg carton idea.

    This is so typical of what happens when you take a car in for service. They always do the easy (for them) and often expensive (for you) part replacement first.

    1. Thanks, Art! I would complain about the mechanic, but the EGR valve did need replacing and the catalytic converter did need replacing.

      And judging from the a totally occluded EGR port in the intake manifold (can you say “insufficient flow”), this was a necessary, even if not sufficient, repair for DEQ approval.

      The car did seem to run better last night. :-)

      I’ll know later today whether I was completely successful.

  2. Hi Brent,
    We have a 2001 Odyssey with 155,000 miles on it.  And that darn light, too.  Sometimes the Traction Control light comes on, too.  Anyway, at the AutoZone, the readout had that same code (P0401).  I’m wondering if I take my van in and tell the mechanic exactly what’s wrong, they would fix it correctly.  I’m not certain I’m confident enough to do all the work on my own.  I’d appreciate your thoughts.
    Many thanks from Kansas…

    1. Boy, does that sound familiar.

      If you’re not comfortable doing this repair yourself, I highly recommend your telling your mechanical about it. I had my car in multiple times before I found this fix. My mechanic had no idea. (To be fair, the catalytic converter and EGR valve did need replaced. But fixing both of those did not fix the problem.)

      Good luck!

  3. Hi Brent. Thanks for the help with this. When I was done I just tightened down the bolts. Now I am thinking you mention torque specs but they are not mentioned in the YouTube video and I am having no luck finding them elsewhere. Could you help me out here? Again thanks for the great post. Rick

  4. End plates on intake manifold – 8.7ft. lbs.

    IAT sensor bolts – 13 ft. lbs

    Boost plate (cover on back of manifold that brake booster vacuum hose attaches to) – 8.7ft. lbs

    EGR nuts, Intake Manifold bolts (bolts in the center 12mm) and throttle body bolts/nuts are torqued to – 16ft. lbs. (22Nm)

  5. This was very helpful. I have an ’01 odyssey with all the same symptoms. I followed your advice, with a little help from the Chiltons manual and solved the problem in an afternoon.

    1. I’m so glad it worked for you.

      The bad news is that if you don’t take it to the dealer to have the EGR port reamed and a Teflon insert installed (as described in the service bulletin), you will have to repeat this later. So far, I’ve done it twice. The good news is that next time around, you’ll do it even faster.

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