How to fix a po411 code on 06 Buick Lucerne V8

The secondary AIR (Air Injection Reaction) system is an emission control system that injects fresh air into the exhaust manifolds to continue the combustion process as the exhaust gasses are leaving the engine. There's a few things that can trigger a P0411 code. A bad secondary AIR pump, bad check valve, damaged AIR system hoses or piping, or even a blown fuse for the secondary AIR pump. The pump on a GM normally sits low under the front bumper and very often gets damaged by water. My first thought is to remove the pump and see if water comes out of it. If it does, replace the pump and check the fuse for the pump. Also perform a visual check of the piping and hoses in the system. Finally, inspect the check valve(s). Remove the rubber hose from the check valve and start the engine. If you have exhaust gasses, which will be HOT, so be careful, coming out of the check valve, the check valve is bad and needs to be replaced. Hope that helps! Jim