Matthew Jackson

P0401 code popped up egr insuffeciat gas return flow I swapped the egr even took off the whole side thermostate housing unit it bolts onto off to clean swapped the gasket for that and the egr swapped exhaust manifolds and code still pops up all I know that's next for me to do is make change the intake manifold gasket and that's my last resort anything else I can do please help thanks.

Colin42

there's egr passages on the intake manifold, they're probably all clogged up, if you do replace the intake gasket make sure you use the right one that has the holes for egr

gts

How typical is it with a P0401 Code that the intake manifold is clogged up?
I've searched the forum and read quite a few posts and threads.

I put got a used D17A2 put into my 2003 EX a few months back and it started throwing the P0401 soon after I started driving it.

I've pulled the EGR valve, cleaned it, and cleaned out of the ports a few times.
Checked the EGR valve and it's working as it should.
I tried putting some Top End into the intake port and letting it sit overnight. Not sure it did much as the port was still "full" the following morning.
After any and/ or all of the above I've cleared the code and it comes back on each time in anywhere from 5-50 miles (more often on the lower end of those miles).

It's starting to warm up up here so I can finally work on the Civic (I don't have a garage and have to do all my work outside).
How likely is it that the intake manifold being clogged up is the culprit? (fwiw the engine has 136k miles on it)

Colin42

Pretty often

gts

Should anything other than the intake manifold plate be replaced when pulling the intake manifold to clean the passages?

Such as the O-rings on the end of the injectors? The throttle body gasket?

I don't want to buy parts that aren't necessarily needed, but don't want to skimp just to save a couple of bucks either.