I agree, check the hoses. If they're still intact and in decent shape, try clearing the codes and doing a drive cycle to see if they codes re-appear/ which ones go away.

 

He had cleared the codes after installing the pump, and drove it well over 100 miles and today the light came back on. That's why we're all so bloody frustrated by it.

 

So what I wonder is which hoses we should check, and their location. Everything is so packed into there so it's kinda difficult to see what's what and where things go.... Does anyone have a diagram of the hoses we should check?

 

2004 GLX V6 engine.

Did the P0442 return after swapping out the gas cap, clearing codes and driving it?

Did you mistype and really mean P0491 & P0492?

Did both of those codes return?

The first is Secondary Air Injection System Insufficient Flow Bank 1 and the second is the same problem but on bank 2. That means something common to both banks is probably at fault. Since you hear the pump running, the fuse and relay that power it are probably functioning.

There is a combi-valve on each head. When the system goes active, these valves open to allow the SAIPump air to enter the exhaust ports in the heads. The combi-valves are operated by engine vacuum which is turned on/off by an electric solenoid. Follow the vacuum lines from the combi-valves to the solenoid. Use a hand vacuum pump to test the lines and solenoid valve. The valve should open when you apply 12vdc to the two contacts on it. Also test the hose from the solenoid to the vacuum source.

When active, the SAIPump blows air through some hoses that lead to the combi-valves. Check these hoses to be sure they aren't cracked/split/melted/disconnected. You can power the SAIPump with 12vdc to the two terminals on the pump (brown lead is negative) and listen to the system pumping air with the engine off. You may be able to hear or feel air leaks in this path.

 

It's probably something related to what Steve is suggesting above. However, before testing the solenoids, check the vacuum lines coming from the back of the engine block with the engine cover off. IF you still have the braided cloth vacuum line, anyone here can guaruntee you at least one of those are broken. Possibly the two that run the combi-valves.

You can replace the vacuum line with some purchased from any auto parts store. Usually you can't see it because they cut the hose behind the counter or in the back. Also, the only secondary air pump hoses that develop cracks are the corrguated ones, one which feeds the pump off of the airbox, and the other which goes from the pump to a metal pipe mounted atop the engine. Make sure that the one at the front of the engine is connected to the metal pipe that feeds the combi valves. The red arrow on this image is where to look:

When you start diagnosing the vacuum system you're looking for this mess:

and the combi valves look like this (not specific one):

and a better view of where they're located on the back of the V6. Look towards the top left and top right corners of the image. You should be able to see them from the top of the engine bay too, just giving you a reference image.

 

As they previously said, the corrugated plastic black hoses crack and its hard to see buried in the engine bay. Take the hose going from the air filter box down to the secondary injection pump and try and blow through it. It should hold pressure. If it doesnt, it will leak through a cracked part of the hose or leak through the combi valve. You should be able to hear where air is escaping and you can shake the hoses a little to help find the leak. If the system is sealed and maintains pressure when you blow on it it is likely a vacuum line or solenoid. I had a cracked hose, I put the two sides together, wrapped one thing of duct tape around and then electrical taped the whole thing because the hose is extremely brittle with the heat and age.

 

Ok, so we found the combi-valve and the one on the drivers side was completely broken. Going to store to buy new. Cross your fingers for us that that's the only issue. Thank you all for your help!

 

How did you determine it's effectiveness without opening it. I've seen them cleaned out

 

I had 0442 from a bad coolant temp sensor. It makes the car run too rich/lean based on reading the wrong temps I assume. Try that, it's basically under the throttle body pipe, and the passenger EGR valve. Plenty of pics around.

I am also suffering from a bank 1 SAI flow problem. Only bank 1 though, p1423. Annoying me to death lol.

 

Err, sorry, it wasn't the combi-valve that was broken, it was the hose that went to the valve that was broken. Sorry! I was just excited we found something and hurrily wrote it. But omg the car is inspected! Thank you all so much for your help! I get my car back!

 

Awesome outcome.:thumbup:

If the vacuum line to the one combi-valve is open, it can leak enough vacuum that both combi-valves won't open. Thus codes for both banks not functioning.

Vacuum line can be bought by-the-foot at most auto parts stores. On older cars the rubber lines have been cooked countless times, exposed to petrochemicals and degrade. Many people just replace as many as they can easily access simply as preventative maintenance.

 

Glad you got your little issue sorted out! :thumbup:

 

x3! glad it got sorted out! Would recommend changing out the other lines too as preventative maintenance!