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Discussion Starter #1 (Edited)
Hi all! First post, but I have been lurking for a while. I feel like this first post may end up a bit long-winded, so I apologize in advance. It's also probably not a great read, but I'm trying to provide all of the info and all of the steps that I took.

So, I recently bought a used 2009 Pontiac G5 with the 2.2L engine, manual transmission, and ~160K on the odometer. I have been systematically repairing check engine lights (CEL) and have arrived at what I hope is the final boss CEL. The particular code that I've been fighting is:

P0411 Secondary Air Injection System Incorrect Flow Detected :mad:

Anyway, I have performed the following diagnostics and checks, mainly in the order listed:
1. Checked air pump function outside of the car . It definitely spins freely and seems to blow a lot of air
2. Checked the output of the air pump hose outlet at the solenoid valve with the pump reinstalled. It again seems like a lot of air blowing out.
3. Replaced the solenoid valve assembly with a brand new unit and gasket. This seemed to be a very common cause for the code according to my internet reading. It definitely did not fix the code.
4. Properly repaired an abysmal "fix" of the flex coupling at the top end of the down pipe. It definitely was leaking exhaust due to what looked like a weld conducted with the pipe in place (how the...?). A friend repaired the weld and I reinstalled the down pipe with new gaskets. It definitely did not fix the code.
5. Checked every fuse and relay that I believed to be associated with the SAI/AIR system. They all seemed fine.
6. Of course, I cleared the codes and conducted many many cold starts. The CEL always returned after two or three cold starts.

At this point and to my mind, this pointed to the issue being somewhere besides:
  • The air pump/smog pump/SAI pump itself
  • The wiring, relays, fuses, etc. that tell the pump to turn on
  • The solenoid valve (unless I got a defective brand new one)
  • Exhaust leaks (unless there's a leak right at the manifold that I haven't found)
So, I moved on to checking out the wiring for the solenoid valve. As I understand it, the wires going to the solenoid valve are the following:
  • Pink/Black-------Solenoid Power
  • Black/White-----Ground
  • Tan----------------Low Reference
  • Brown/White----Signal from Solenoid Pressure Sensor
  • White--------------5V Reference
And so, I proceeded with wiring diagnostics as follows:
1. Checked continuity of the wiring between the solenoid valve connector and the PCM connector.
  • Solenoid Power----------I don't believe I checked this one (see below)
  • Ground---------------------No connection to ground (see below)
  • Low Reference-----------There were far too many tan wires to check
  • Signal-----------------------Good continuity
  • 5V Reference-------------Good continuity
2. Connected the apparently unconnected ground wire to a good ground point
3. Checked voltage at the solenoid valve connector (with it removed from solenoid valve) and with air pump engaged during a cold start
  • Solenoid Power------------14V
  • Ground-----------------------Did not check
  • Low Reference-------------0V
  • Signal-------------------------0V
  • 5V Reference---------------5V
4. Checked the voltage of the Signal wire when the SAI/AIR pump was running and immediately after:
  • Pump running--------------------------------4.10V
  • Immediately after pump running---------2.78V
At this point, I'm not quite sure what to think. I don't know what the output from the Signal wire should be, but it maybe makes sense that it is near full scale (5V) with the pump on. This tells me that the fan turns on and the pressure sensor sees air. Is this not the exact opposite of what the CEL is telling me?!

Anyway, I would greatly appreciate input from anyone who has some thoughts on what may actually be the problem. Thanks!

TL;DR:
Yet another post about P0411. Replaced stuff and checked stuff and the CEL is still on. Looking for unique input.

-Ben
 

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Hi all! First post, but I have been lurking for a while. I feel like this first post may end up a bit long-winded, so I apologize in advance. It's also probably not a great read, but I'm trying to provide all of the info and all of the steps that I took.

So, I recently bought a used 2009 Pontiac G5 with the 2.2L engine, manual transmission, and ~160K on the odometer. I have been systematically repairing check engine lights (CEL) and have arrived at what I hope is the final boss CEL. The particular code that I've been fighting is:

P0411 Secondary Air Injection System Incorrect Flow Detected :mad:

Anyway, I have performed the following diagnostics and checks, mainly in the order listed:
1. Checked air pump function outside of the car . It definitely spins freely and seems to blow a lot of air
2. Checked the output of the air pump hose outlet at the solenoid valve with the pump reinstalled. It again seems like a lot of air blowing out.
3. Replaced the solenoid valve assembly with a brand new unit and gasket. This seemed to be a very common cause for the code according to my internet reading. It definitely did not fix the code.
4. Properly repaired an abysmal "fix" of the flex coupling at the top end of the down pipe. It definitely was leaking exhaust due to what looked like a weld conducted with the pipe in place (how the...?). A friend repaired the weld and I reinstalled the down pipe with new gaskets. It definitely did not fix the code.
5. Checked every fuse and relay that I believed to be associated with the SAI/AIR system. They all seemed fine.
6. Of course, I cleared the codes and conducted many many cold starts. The CEL always returned after two or three cold starts.

At this point and to my mind, this pointed to the issue being somewhere besides:
  • The air pump/smog pump/SAI pump itself
  • The wiring, relays, fuses, etc. that tell the pump to turn on
  • The solenoid valve (unless I got a defective brand new one)
  • Exhaust leaks (unless there's a leak right at the manifold that I haven't found)
So, I moved on to checking out the wiring for the solenoid valve. As I understand it, the wires going to the solenoid valve are the following:
  • Pink/Black-------Solenoid Power
  • Black/White-----Ground
  • Tan----------------Low Reference
  • Brown/White----Signal from Solenoid Pressure Sensor
  • White--------------5V Reference
And so, I proceeded with wiring diagnostics as follows:
1. Checked continuity of the wiring between the solenoid valve connector and the PCM connector.
  • Solenoid Power----------I don't believe I checked this one (see below)
  • Ground---------------------No connection to ground (see below)
  • Low Reference-----------There were far too many tan wires to check
  • Signal-----------------------Good continuity
  • 5V Reference-------------Good continuity
2. Connected the apparently unconnected ground wire to a good ground point
3. Checked voltage at the solenoid valve connector (with it removed from solenoid valve) and with air pump engaged during a cold start
  • Solenoid Power------------14V
  • Ground-----------------------Did not check
  • Low Reference-------------0V
  • Signal-------------------------0V
  • 5V Reference---------------5V
4. Checked the voltage of the Signal wire when the SAI/AIR pump was running and immediately after:
  • Pump running--------------------------------4.10V
  • Immediately after pump running---------2.78V
At this point, I'm not quite sure what to think. I don't know what the output from the Signal wire should be, but it maybe makes sense that it is near full scale (5V) with the pump on. This tells me that the fan turns on and the pressure sensor sees air. Is this not the exact opposite of what the CEL is telling me?!

Anyway, I would greatly appreciate input from anyone who has some thoughts on what may actually be the problem. Thanks!

TL;DR:
Yet another post about P0411. Replaced stuff and checked stuff and the CEL is still on. Looking for unique input.

-Ben
Hi Ben: Is what you call the solenoid valve what is otherwise called the check valve assembly? In my case, I confirmed the air pump was blowing good and hard by disconnecting the hose to the check valve, having someone else start the car, and putting my hand right in front of the hose running into the check valve. Plenty of air blowing and no need to take the air pump off the car and put it back on. No need to check the air pump fuse, relay, etc. etc. So the problem seemed to be located in the check valve or perhaps in the pressure sensor which is incorporated in the check valve assembly. First I took off the existing check valve assembly and cleaned it out with carb cleaner spray, sprayed into the opening into the exhaust to attempt to clean carbon out of there and sprayed into the downpipe towards the airpump (which may or may not be a very good idea). Still didn't work.

Then bought new check valve, installed it (first time did not install it properly and had exhaust leak back into the engine compartment but redid the installation and got it right). Cleaned out electrical connector with spray, and then applied dielectric grease, reconnected and P0411 was gone. Sounds like you still have an electrical problem leading to the check valve, or you have carbon buildup someplace entirely blocking the air flow; perhaps in the hole leading down to the exhaust pipe.

Maybe I am off base but based on my replacement, I don't know what else, other than those two possibilities it could be.

Sorry, that is it based on my experience. Reuben
 

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Hi Ben: Is what you call the solenoid valve what is otherwise called the check valve assembly? In my case, I confirmed the air pump was blowing good and hard by disconnecting the hose to the check valve, having someone else start the car, and putting my hand right in front of the hose running into the check valve. Plenty of air blowing and no need to take the air pump off the car and put it back on. No need to check the air pump fuse, relay, etc. etc. So the problem seemed to be located in the check valve or perhaps in the pressure sensor which is incorporated in the check valve assembly. First I took off the existing check valve assembly and cleaned it out with carb cleaner spray, sprayed into the opening into the exhaust to attempt to clean carbon out of there and sprayed into the downpipe towards the airpump (which may or may not be a very good idea). Still didn't work.

Then bought new check valve, installed it (first time did not install it properly and had exhaust leak back into the engine compartment but redid the installation and got it right). Cleaned out electrical connector with spray, and then applied dielectric grease, reconnected and P0411 was gone. Sounds like you still have an electrical problem leading to the check valve, or you have carbon buildup someplace entirely blocking the air flow; perhaps in the hole leading down to the exhaust pipe.

Maybe I am off base but based on my replacement, I don't know what else, other than those two possibilities it could be.

Sorry, that is it based on my experience. Reuben
One more question: isn't a new flex coupling part of the new check valve assembly you purchased? On mine the small flex pipes were part of the assembly and thus I had new flex pipes as well as the check valve itself. Again, you replaced the entire check valve assembly?
 

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Discussion Starter #5
Hi Ben: Is what you call the solenoid valve what is otherwise called the check valve assembly? In my case, I confirmed the air pump was blowing good and hard by disconnecting the hose to the check valve, having someone else start the car, and putting my hand right in front of the hose running into the check valve. Plenty of air blowing and no need to take the air pump off the car and put it back on. No need to check the air pump fuse, relay, etc. etc. So the problem seemed to be located in the check valve or perhaps in the pressure sensor which is incorporated in the check valve assembly. First I took off the existing check valve assembly and cleaned it out with carb cleaner spray, sprayed into the opening into the exhaust to attempt to clean carbon out of there and sprayed into the downpipe towards the airpump (which may or may not be a very good idea). Still didn't work.

Then bought new check valve, installed it (first time did not install it properly and had exhaust leak back into the engine compartment but redid the installation and got it right). Cleaned out electrical connector with spray, and then applied dielectric grease, reconnected and P0411 was gone. Sounds like you still have an electrical problem leading to the check valve, or you have carbon buildup someplace entirely blocking the air flow; perhaps in the hole leading down to the exhaust pipe.

Maybe I am off base but based on my replacement, I don't know what else, other than those two possibilities it could be.

Sorry, that is it based on my experience. Reuben
Reuben, thanks for the response and definitely don't apologize for trying to help! And to clarify things I did mean the check valve assembly when I said "solenoid valve". As I understand it, the check valve assembly contains a check valve, a solenoid valve, and a pressure sensor. Anyway, my very next step is to try to clean and dielectric grease the various connectors and cross my fingers that it clears things up.

One more question: isn't a new flex coupling part of the new check valve assembly you purchased? On mine the small flex pipes were part of the assembly and thus I had new flex pipes as well as the check valve itself. Again, you replaced the entire check valve assembly?
I was actually referring to the flex coupling that is part of the exhaust down pipe and bolts to the output of the exhaust manifold. According to partsgeek, it looks like the SAI check valve assembly changed designs at some point (see attached) and the new design did away with the separate flex hose. Also, yes, I replaced the entire check valve assembly.

OLD:
19525


NEW:
19526
 

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Hi Ben
I went thru something similar last year on my 2006 In my case it turned out to be the solenoid valve and the upstream O2 sensor - but i also got the O2 code I Don't want to lead you down the wrong track - so take this with a grain of salt The way I understand these things work is the pump turns on and runs for about a minute with the valve open to add extra air into the exhaust while the engine is running rich to preheat the cat - less when its warm out - then the valve closes and the sensor looks for a rise in pressure - when it see the pressure go up it turns the pump off - you mentioned hearing some sort of exhaust leak - I'd make sure its not on the pump side of things or you won't get the pressure rise its looking for
The manual says first inspect AIR hoses /pipes between pump when code is set
then with the engine running verify the air pressure is 20-25 kPa above Baro - real helpful
anyway
Hope this helps
JP
 

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Got it
Reuben, thanks for the response and definitely don't apologize for trying to help! And to clarify things I did mean the check valve assembly when I said "solenoid valve". As I understand it, the check valve assembly contains a check valve, a solenoid valve, and a pressure sensor. Anyway, my very next step is to try to clean and dielectric grease the various connectors and cross my fingers that it clears things up.


I was actually referring to the flex coupling that is part of the exhaust down pipe and bolts to the output of the exhaust manifold. According to partsgeek, it looks like the SAI check valve assembly changed designs at some point (see attached) and the new design did away with the separate flex hose. Also, yes, I replaced the entire check valve assembly.

OLD:
View attachment 19525

NEW:
View attachment 19526
Got it. I replaced the old style check valve assembly with the one flexible metal line. And that was what I thought you were referring to when you said there was a hole in it that was soldered. But now I got it. The new part doesn't match the old part I took off of my 2008 Cobalt LS, so I replaced like with like. I hope the cleaning of the electrical connector or solving a carbon buildup issue with solve the problem for you. Best of luck. Reuben
 
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