Billman250

We all know this code, P0411, which everybody gets after installing an intake. Usually crossed vac lines or a backwards white check valve.

So while I'm doing a motor job, I decide to tackle the CEL which has been on for a long time. The guy even has "Check engine light" in his sig

BTW...I tried the flow of diagnostics in the Honda manual for 411 and the book is way off. Anybody who knows this stuff, read it carefully and you'll see why.

Anyway.....I hear the pump run when the car is cold, go over the lines and the check valve. All is good, except I don't like the way some of the lines fit as they were not the grey Honda lines that fit nice and tight. So I replace them, still get P0411 pending right away. Right away I suspect the Vaccum Control Valve, which is the little valve behind the Air Pump in the pic. (originally mounted to the airbox)

The valve clicks on and off, I can feel it. So I do my own tests, the valve opens and closes fine, and allows vac to pass at the right time. Still suspicious, I put the valve in my car and start it up, get P0411 pending right away in MY car. so I replace the valve thinking I've got it pegged, and realize this is not the only problem, but what cause the next as well.

The last think to check is the pump. It's sounds like it's spining pretty fast, with little resistance. I'm sure the ELD unit picked up on it and triggered the CEL.

Sure enough, I pull the bumper and find the pump housing had burned through, but the motor was ok and sounded fine. Enjoy :

Slows2k

You found the air leak, just not in a typical place. Could you feel any air escaping the bottom of the fenderliner with the pump running?

Billman250

Couldn't feel any air coming out. He went to the dealer and told them he smelled burning plastic, they couldn't find anything

goldenfri

Very interesting, I have had the 411 CEL on my car for a while and haven't been able to fix it yet. I will have to check that

Billman250

check the vac line routing, tightness, and white check valve (going the right way) first, almost always the case....

JDM S2000

i can not get rid of the p0411, Ive read and tried everything on here and now my car makes a huming noise near the intake

Wisconsin S2k

you have a thread about this already. please limit your discussion to that thread, rather than trying to spam other threads with your problem.

supermario300hp

I have a Po411 and for some reason my car will not go into VTEC. Is there any relation? It is the only code that is coming up on, and I dont know what to do.

Billman250

Totally not related.

1320performancefreak

interesting. well i had the code ever since i bough my car and guess what it does not even have the air pump system. so hopefully this weekend i can install my new air pump on and get rid of the annoy cel.