P0411 [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: P0411


eman0006
08-13-2008, 10:59 AM
Hey guys, I started my truck after work a few days ago and the check engine light came on immediatley. I bought a scan tool the next morning and pulled code P0411 (Secondary air injection incorrect upstream flow detected). I have reset the light twice and it will stay off until the truck sits for 6+ hours then it will come back on again when I start the truck.

I have read a half dozen threads on code P0410 but have found information on code P0411 limited. My question is should I be treating this code the same way as P0410 or does the code P0411 open up a new can of worms?


thank you

eman0006
08-13-2008, 11:00 AM
I filled out all of the information on my profile but it did not seem to pop up

I have a 2006 Trailblazer with the 4.2L

rbarrios
08-13-2008, 04:13 PM
did you read this thread?

maybe you can take the valve off and look at it...
I think others say they rust internally...
may be worth your while to take it off and check it...

http://forums.trailvoy.com/showthread.php?t=44278&highlight=P0410

eman0006
08-13-2008, 05:03 PM
Yes I read that thread which is what put me onto the check valve in the first place.

I was just curious because everyone else under the sun pulls a code P0410 and for some reason I have to be different and pull code P0411.

Some additional info, last night when I left work I started my truck and I heard the pump run for about 5 seconds.

With the light reset I went out at lunch today and started my truck, the light did not come on which I assume means the engine was not cool enough. But I had the hose pulled from the check valve and I felt and heard the suction for about 5 seconds then it went away.

thanks
Tim

jamesm2005
11-05-2009, 08:54 PM
Yes I read that thread which is what put me onto the check valve in the first place.

I was just curious because everyone else under the sun pulls a code P0410 and for some reason I have to be different and pull code P0411.

Some additional info, last night when I left work I started my truck and I heard the pump run for about 5 seconds.

With the light reset I went out at lunch today and started my truck, the light did not come on which I assume means the engine was not cool enough. But I had the hose pulled from the check valve and I felt and heard the suction for about 5 seconds then it went away.

thanks
Tim

Hey Tim,

Did you get this problem fixed? I have been dealing with the Check Valve issue on my 06 Trailblazer for a while now too.

This seems to be a big issue and it is going to be one of three things. Either your secondary air pump (under the floor of the driver side), the relay for this air pump (next to air pump), and then the check valve which is supposed to open and close on a cold start (engine off for at least 4-6 hours).

I would bet that your check valve needs to be replaced.

The newer trailblazers check valve is more sophisticated than the earlier TBs with this issue. I believe that your check valve now has a pressure sensor that the previous TBs do not.

There is a really good, but long thread about this problem.

I am still working on mine only because I dont have the money to order the check valve yet, but should be doing this soon.

Here is that thread:
http://forums.trailvoy.com/showthread.php?t=45668

I see you are in Eagan, MN. Im in Minneapolis. Ill race you to the nearest junkyard! :)

If you already fixed this problem, it would be good to hear what you did.

SBUBandit
01-20-2010, 03:47 PM
Just had this on mine this Saturday, took it in on Monday, and they replaced the check valve, but when they went to fire it back up they had problems with the computer not seeing ground, so my truck got a new PCM as well. At least it was all covered

SCOOT
02-16-2010, 06:57 PM
Any updates?? I just threw this code on my 06 4.2 aswell..

Heres my case. Ever since i installed my Volant CAI it has been idling etremely rough on cold starts untill i hear what sounds like a vacuum pump come on (a high pitch humming noise) then it runs perfect. Its been doing this since late august of last year and it just now threw a code for the secondary air induction fault (p0411).. Think they are related?? Where is the check valve located?

the roadie
02-16-2010, 08:31 PM
The check valve is on the exhaust manifold. A long discussion with diagrams of the locations of the parts is in the thread referenced in post #5:

http://forums.trailvoy.com/showthread.php?t=45668

The turbine air pump hastens the vehicle getting into closed loop mode on a cold start. You might need other things that affect idle, like cleaning the throttle body (some folks need to do it every 30K miles!) or new plugs.

http://forums.trailvoy.com/articles.php?do=viewarticle&artid=91

DocShea
04-20-2013, 06:54 PM
Ok, got the same code p0411. Issue started 3-4 days ago. I turn on the envoy (cold start) and hear the really loud secondary air pump run for 20-30 seconds then it slows down to a stop. About 2 months ago I replaced the o2 sensor located close to the trans stick. Cleaned the throttle body, and had to replace the wire harness and board in my heating/cooling fan. Ran great. However, now as I stated the new code is showing. Took apart the hoses below the drivers side and no water came out. Took the Solenoid valve off, took it completely apart and cleaned it then sprayed penetrating lube in it and let it soak (not sure if it works though) I don't have any electrical jumpers or a 12v battery to test if it's operating or not. Put everything back together and same problem. Any ideas on what I should try next? Advice and pictures are greatly appreciated:)
2006 GMC Envoy, 4wd, I6., 4.2L.

Bobsgarage
03-08-2016, 10:34 PM
Hello all, I'm new to this forum. I too have dealt with this code p0411 on my son's 2007 trailblazer 4.2L.

The first thing you need to know on 2006 and later models is that the pressure sensor in the solenoid shut off valve is what the ECM uses to determine flow and it is looking for a certain range of pressure above barometric pressure. Barometric pressure is around 98 to 100 kpa in my area and the ECM wants to see 8 to 10 kpa above that during operation so 106 to 108 kpa is the target pressure.

Fixing this problem may require a capable scan tool assuming all components can be determined to be operable, because you need to know if the pressure is high or low.

I wound up purchasing a scan tool with bidirectional capability to have the enhanced live data and control over the pump and solenoid valve to sort this out.

In my case I had a high pressure issue after replacing the pump, relay, and solenoid valve. The lines were clear and were not leaking. All components were operational, including the check valve, which can be verified by watching the upstream o2 sensor while manually operating the system. The sensor will be driven full lean when the pump runs.

When you have a high pressure at the solenoid valve, it is either the valve not opening, the check valve has too much resistance to flow, or the port in the head is clogged. I cleaned the port while replacing the valve, which had a new check valve in it and ran the engine to confirm that exhaust would blast out of the port and clear it.

The pressure was at 115 kpa while the system ran on cold start after all this. At my wits end, I had to do a work around. I had to drill holes in the pressure hose on the bottom side near the valve to create enough leak to lower the pressure to 109 kpa. The upstream o2 sensor still drives full lean while the pump runs, and P0411 is GONE!!!!!!!!