I have a 2015 GMC Terrain with the 2.4L Ecotec motor Cali emissions. I got a code P0411 for the AIR system flow. I went to dealer to get part information and ordered parts online with the OEM part numbers. I replaced the air pump and both solenoid valves. Code is still setting. I Pulled the hose on solenoids and started up when cold, found air pump is operational and valves are opening because I can feel the exhaust puffing out the solenoid when open. Is there a bulletin or another issue that can cause this problem?

What testing have you done?

I verified pump operation, solenoids operation and there is no blockage in ports.

Did you reset the code after repairs were made?

How many miles on the vehicle?

I have cleared the code several times with my scan tool. But will reset immediately on cold startup. Vehicle has about 83k miles. I did see a GM bulletin posted for P0411 but I was not able to open the bulletin to read it. Does anyone know what this bulletin is referencing? I know in the past the exhaust manifolds would crack on the older ECOTEC motors and I am wondering if this might be an issue. I would have to remove the heat shield to see if it is cracked. I was a GM tech for 15 years, but been out of the business for 6 years and have no access to any information anymore.

Check the ears on the manifold.

I have also seen these motors breaking studs on the manifolds on the Saturn ECOTEC motors. I will have to take a closer look at the manifold

I don't think a cracked manifold will cause this a P0411, unless it is cracked all the way off and on the ground in pieces.

A lot of folks are fixing this on these by replacing the one-way check valve.

Definitely the secondary check valve

as listed above I replaced the solenoid/check valve. The check valve is part of the solenoid. I replace air pump at the same time. I verified operation of pump and check valves.