Conquering Code P0411 Your Step-by-Step Troubleshooting Manual

The light may or may not go out on its won, Chevy computers store codes until they are cleared out with a code reader, I'd say go to a parts ... The car will run approximately 20 to 30 minutes and will start to shake and shut off. We replaced the throttle body due to launch scanner stating it was ... The 4 way control line splitter AND 3 way splitter are cracking/splitting. You need to apply 15PSI to pressure test all the intake system. If your getting this code it can be 2 things the smog pump is bad (most likely as it sits in a bad area that collects water) or the $40 control ... It is hard for the system to detect the failure( small leak, air pump started to burn out or short in wiring harness for air injection system). P0411 (Secondary air injection incorrect upstream flow detected). I have reset the light twice and it will stay off until the truck sits for 6+ hours then it ... UPDATE: seems the secondary air injection combi valve; was stuck and needed to be replaced, to fix the trouble code. Testing and replacement ... I know its a 2 stage test, with part of it being valve open and pump on and then part pump on and valve closed and I know the pressure increases the vehicle is ... The 4mm inside diameter vaccuum hose gets pinched between the lower intake manifold and the secondary air pump housing, flattening it over time. The overall code seems to be related to secondary air injection so I thought perhaps this might be the turbo diverter valve.