P1444/P1445 - Secondary Air Injection System (1 Viewer)

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Joined
Sep 6, 2007
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374
Location
Nashville, TN
Website
www.4wdlexus.com
Wanted to post my experience with the dreaded P1444/P1445/P1441/P1442 Secondary Air Injection System Switching Valve Stuck Close/Open Bank 1/2. This is on an 06 GX, and I think this only applies to 06+ VVTI engines.

In some quick reading, I saw that the main culprit was the air pump under the intake manifold. So after confirming the issue remained after checking the VSVs and clearing the code, I dove in and removed the intake manifold. Air pump and main valve can be seen in the valley in front of starter:
IMG_2695.jpg


Removing the manifold is tedious, etc, but as expected. The part that needs to be documented for us GX 06+ VVTi owners is that the secondary valves are located at the back of the engine within an inch of the firewall with the engine wiring harness in the way. If your problem is the air pump, no problem, tackle it and consider the alternative GM pump that is mentioned on the web. However, if your problem is the secondary switching valves, think long and hard about performing the work yourself.

With the manifold removed, I spent 3 hours removing other parts and just plain staring at it, I don't think it's possible to remove the valves without lowering the engine or tilting it forward to gain access. The two valves at back of engine require removing two bolts that come from the rear toward the front and two bolts that come from the left and right toward the center of the vehicle:
IMG_2696.JPG


Maybe there is a technique that I'm missing, but I would not tackle this job again. Your mileage may vary. Unless I learn something in the next day or two, I'll be reassembling as-is and buying the bypass kit online to fool the computer. This air injection system only operates under certain temp ranges and only during the first minute or two during cold start to help warm up the catalytic converters quickly. Emissions ridiculousness on a 10 year old truck.

Anyway. Wanted to document for others. And please chime in if someone knows a trick to remove the valves!
 
Last edited:
Please, keep us updated on this.
 
Looks like a nightmare to get to.

I believe the VVTi started with the 05 vehicles.
 
just ordered the plug and play kit yesterday. No way do I have time to tear my engine apart to replace the item that will fail again.
 
I have an 03, what is that thing? :p
 
I can confirm the issue starts with the 2005 Models. I have a 2005 and I have one of the bypass setups. Reading this thread confirms I made the right choice.

Thanks for the writeup just the same. It really gives people an idea of what is involved. My issue was the valves, and not the pump. I'm not sure I would even bother with it if it was the pump.
 
'05 vvti here as well, running the bypass without issue. Just passed inspection last month. might want to rebuild your starter while you have the intake off. Cheers!
 
I ordered the by-pass today, the plug and go one on eBay, not having any problems or codes, but just getting ahead of this.
 
Yup I have an 05 that had the issue and got the bypass kit, all good now.
 
Just wrapping up to confirm the bypass kit is the right decision. I'd really like to know what the Lexus dealer does to change these secondary switching valves. But for me - I buttoned it back up, and installed the bypass kit from Hewitt Tech (Hewitt Technologies Inc. - Store) - paid a little more than the eBay kits, but don't have to worry about my wife leaving the key "on" too long before cranking due to the starter connection that this kit offers.

Really hate having a bypass kit - but this is definitely the right choice for this issue on the GX. I think i have close to 11 hours in this project, but hey, coolant is changed and fresh manifold gaskets are installed(!).

Tried to grab additional pics of the valves for other's reference:
IMG_2699.jpg
IMG_2701.jpg


And the bypass kit installed:
IMG_2706 (1).jpg

IMG_2707.jpg
 
Just wrapping up to confirm the bypass kit is the right decision. I'd really like to know what the Lexus dealer does to change these secondary switching valves. But for me - I buttoned it back up, and installed the bypass kit from Hewitt Tech (Hewitt Technologies Inc. - Store) - paid a little more than the eBay kits, but don't have to worry about my wife leaving the key "on" too long before cranking due to the starter connection that this kit offers.


What do you mean worry about my wife leaving the key "on" too long before cranking? What is the concern there?
 

"What do you mean worry about my wife leaving the key "on" too long before cranking? What is the concern there?"


It's not a big deal, but the bypass kits will "timeout" after around 10 secs of the key being in the "ON" position. Then, if you crank it without going back to "OFF" first, the air injection system will try to operate (if all other conditions indicate that it should operate). Hewitt's kit, and maybe others, add a connection to the starter relay to overcome this. Again, not a big deal if it's you driving the GX, but with others driving it may prove useful.
 
My wife rarely ever drives my truck but murphy's law dictates that this would happen the one time she did. This mod is at the top of my list now. Thanks for the info!
 
Just popping this back up to ask about the manifold removal. The only instructions I could find were copied from the Toyota manual, which states to first drain the coolant. I can't see why this is necessary, but anyone that has removed the manifold, can you spread some light?
 
"What do you mean worry about my wife leaving the key "on" too long before cranking? What is the concern there?"

It's not a big deal, but the bypass kits will "timeout" after around 10 secs of the key being in the "ON" position. Then, if you crank it without going back to "OFF" first, the air injection system will try to operate (if all other conditions indicate that it should operate). Hewitt's kit, and maybe others, add a connection to the starter relay to overcome this. Again, not a big deal if it's you driving the GX, but with others driving it may prove useful.

Question - So if you left the key on too long and the system timed out it would then trigger the code? and if that is case, you could then just clear the code and be on your merry way like nothing happened?
 
Just popping this back up to ask about the manifold removal. The only instructions I could find were copied from the Toyota manual, which states to first drain the coolant. I can't see why this is necessary, but anyone that has removed the manifold, can you spread some light?

As I recall, the only reason to drain the coolant is if you completely remove the throttle body from the front of manifold. You can leave the coolant hoses connected and simply lay the throttle body over to remove the manifold. Good luck!
 
As I recall, the only reason to drain the coolant is if you completely remove the throttle body from the front of manifold. You can leave the coolant hoses connected and simply lay the throttle body over to remove the manifold. Good luck!

Thanks! I just need to swap a knock sensor, so the manifold removal will be the most difficult part.
 
"What do you mean worry about my wife leaving the key "on" too long before cranking? What is the concern there?"

It's not a big deal, but the bypass kits will "timeout" after around 10 secs of the key being in the "ON" position. Then, if you crank it without going back to "OFF" first, the air injection system will try to operate (if all other conditions indicate that it should operate). Hewitt's kit, and maybe others, add a connection to the starter relay to overcome this. Again, not a big deal if it's you driving the GX, but with others driving it may prove useful.

Question - So if you left the key on too long and the system timed out it would then trigger the code? and if that is case, you could then just clear the code and be on your merry way like nothing happened?

If not started directly from the off position (only important on cold starts, ignition off for 7 hrs or longer) you would need to cycle the key as mentioned before starting to ensure the module is active during cranking. The starter sense wire was originally designed to be optional but but our units are now only active for a fraction of a second which greatly reduces the impact on startup fuel trims. We used to go into great detail about them but it caused more confusion and now it is pretty much just install the sense wire and forget about it.
 

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