I had a P0404 CEL light. I initially cleaned the EGR valve but the CEL came back immediately. I proceeded to replaced the EGR valve and the car ran fine for a few days but the CEL light returned. I did have the symptoms of the light pinging at cruise and at light throttle. I followed the instructions on this post and found that all four ports on the EGR chamber was block! I have attached photos before the cleaning! I followed your instructions and throughly clean and reassembled the EGR chamber. I am sure this will solve my CEL light but I will report back in a few days.
Not sure if the EGR replacement was necessary or does a failed EGR cause this type of carbon built-up?
Meant to post earlier ... really nice info ... I did my ports and got out a lot of carbon, even though I could see each of the four holes was still open. Car runs great, thanks all!
my 2006 Civic hybrid has 225,000 plus miles and have had pinging for about the last 20k miles..
had 1/2 inch of Carbon build up .. both inner cover and lower 4 holes were filled and i had to chisel it all out and now super excited to see how this improvement will result !
Im reading this thread and looking at the Dropbox pics AFTER I cleaned the EGR ports yesterday.
I wasn’t very cautious about letting the loosened debris fall into the coolant as I now see I should have been.
The car runs fine so far (I only drove it a little yesterday after cleaning the Egr chamber, and then a little again today after changing the spark plugs) but I have a small coolant leak from a small hose just below the Egr valve. Maybe related to me contaminating the coolant, I don’t know. I don’t even know what the hose is or where it goes to/from. I’m pretty sure it wasn’t leaking before. But my bigger concern is what is the potential damage from the loosened carbon debris having gotten into those channels?
I wish I’d consulted this thread and those pics before I did the job!
Thanks for the quick response- and for posting the how-to originally!
When you say flush, do you mean simply a drain and refill or a more involved flushing of the entire system?
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