Need help diagnosing a P0411 Secondary Air issue

[guitarfish]

OK, here's the deal. Money's tight, and dropping the car for for $100 diagnosis is something I'm trying to avoid. The check engine light popped on a few weeks ago in my 2008 Prix, and never went off. The code thrown is a P0411, Seconday Air.

A few years back I had a P0410 in my '02 Prix, and the issue was the air pump - it was full of water. However, in researching the P0411, a number of people online have had issues with the check valve being stuck closed.

Today I pulled off the hose that goes from the air pump to the check valve and started the car. I could hear the air whistling through the air pump, and feel a strong gust coming out the hose. With regard to water, I got a small amount of mist that blew out the hose, but that's it. It seems like the pump is doing it's job and not waterlogged.

I have no scan tools and I probably can't do much more diagnosis at home in my garage, but I'm thinking my issue is the check valve. A new one runs $190.

Do I make an educated guess and install a new valve? What do you guys think?

[procaddytech]

More than likely it is the check valve. On an 08 it is a check valve and also contains a pressure sensor for self diagnostics. Without a scan tool you can't command it on and off and compare the pressure difference against barometric pressure like the vehicle does.

[guitarfish]

Just wanted to post back. I changed the check valve. I then removed the neg battery cable for about an hour, and when I reconnected it the SES light was out. I've made about four trips and driven >150 miles since then, no SES light, so I think it's fixed.

When shoipping got the check valve, I found that GM sells it as a unit attached to a heavy steel mounting bracket, which includes a metal tube that connects to the exhaust. And they also sell just the check vale, without the bracket & tube. The latter one is a little cheaper.

I was able to buy a new one, bracket and all, on eBay motors.

From what I could tell, installing the check valve with bracket is a very major job. I couldn't even see where the bottom bolts were on the engine because there was another heavy chunk of steel in the way. Instead, I removed check valve from the bracket on the car, and installed the new one. It's a slow process, but doable. Disconnecting the front/top engine struts and pulling it forward is a must.