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About 13 months and 7500 miles ago, my mechanic replaced the EGR Valve and Tube and cleaned the intake to solve the low airflow problem. Now I'm again getting an insufficient flow warning with my check engine light (code P0401). I noticed the light shortly after rapidly accelerating because of a short merge lane in temperatures around 90 degrees.

My main question is: Is there anything else that wasn't replaced or cleaned last year that could be causing the problem?

Also, I know Accords like mine have problems with buildup in the EGR system. But has anyone else experienced repeat problems with the EGR system within such a short timeframe?

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If this is the V6 Accord, it very well could be an issue with carbon buildup again. It seems there was a tech bulletin which was issued by Honda about it for the 98-01 Accord and 99-02 Odyssey.

I found a pretty write-up of how to get it really cleaned up, as getting it into a good state is quite a bit of a job. Here is where the write-up can be found with pictures. Here is the basic write-up pulled from that website:

You will need; wire brush, some carb cleaner or brake cleaner, a shop vac, new EGR gasket $1-$2 and new EGR chamber gasket $32.00 from Honda.

  1. Remove the fuel rail with the injectors intact if possible. (Do it slow and gentle)
  2. Unbolt the EGR valve.
  3. Unbolt the EGR chamber underneath the fuel, that is bolted on to the intake manifold.
  4. Soak the EGR chamber with a cleaner and scrub the hell out of it, this took me a while as you can see how dirty it was. I mean it was hard as a rock at some spots.
  5. Use the shop vac to suck the carbon build up as you break it away on the intake manifold.
  • Thanks! This answer will be helpful to people searching this site. But what I'd really like to know is why the problem has resurfaced so quickly. My Aunt had the valve replaced I think around 50k miles, and then my mechanic replaced it around 160k miles (along with cleaning the intake and replacing the tube). So why does the problem resurface again at 167.5k miles? – SAG Sep 6 '15 at 0:13
  • It probably recurred because the mechanic didn't do a thorough job of cleaning it when he replaced the EGR the last time. If it was as plugged as the write-up on the website shows, it could easily have plugged again. You aren't the only one to have seen this problem, obviously. Honda wouldn't have put out a tech bulletin if it didn't happen but once in a while. – Pᴀᴜʟsᴛᴇʀ2 Sep 6 '15 at 0:15
  • Yes. I agree that it could have been the mechanic not doing a thorough job (they forgot to put the cap back on the radiator when they did the timing belt). But I just want to be sure that it's not something else going wrong in the emissions system (or somewhere else) that is causing quicker than usual buildup. Do you know of anything else that could be causing unusually quick buildup? – SAG Sep 6 '15 at 0:24
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    With all due respect, Honda screwed the pooch when it came to their design ... Not much else to say. – Pᴀᴜʟsᴛᴇʀ2 Sep 6 '15 at 2:10
  • That makes me wonder if there are any better aftermarket alternatives that still meet emissions requirements. By the way, are there any mechanics in your area who you would trust to do a proper cleaning? I'm about an hour north of you, but it might be worth the drive so that I have a better chance of avoiding another repair so soon. – SAG Sep 6 '15 at 3:29
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Most people just clean the EGR port with a small drill and think they are done. Just inside where the throttle body mounts They are 2 side passages that are often overlooked. I had to bend a wire and dig them out. They were stopped up solid. I also took a pressure washer to the plenum. Lots of gunk and carbon came out. Hope this helps someone.

Gene

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A properly done repair for this should last for at least five years, repeats are rare, and I have done a lot of these.

A repeat plugging is most likely due to poor cleaning the first time. If the updated tube was installed and it was properly cleaned consider these possibility's. 1) Excess oil getting into the intake from the PCV system, or other causes of oil consumption. 2) Poor fuel that does not have good cleaners. 3) Unusual driving habits, especially short trips. 4) The EGR valve is sticking closed, but this should set a different code. All rare but possible.

Was the update tube really installed? It requires special tools, we see this left out sometimes. This tube really does help the carbon buildup. If this car is in my service bay this is the first thing I would check

By the way the EGR valve does not affect the plugging, we rarely replace them after the first updated one is installed.

  • Thanks! The work order lists that the tube 19505-P8A-A00 was used. Is this the right tube? – SAG Sep 7 '15 at 13:45
  • That is a coolant pipe in the general area of the EGR valve but not related to it. The tube I referred to has no part number but part of a kit that may or may apply to your exact vehicle. there is a TSB available that has the details and it varies by model. – Fred Wilson Sep 7 '15 at 16:14

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