TimTaylor

Anybody?!?! P0401 & P0411 What could be making both of these go on at the same time consistently and what could be giving me a rough start wen it's warmed up?

Thanks all

silveradobeast

i have the same problem im still trying to figure it out

sylver91

So P0401 is low EGR flow, possible the EGR is build up with crud, low vacuum or the differential pressure feedback.

And P0411 is secondary air injection incorrect upstream flow. I'd check your air pump is working, no holes in exhaust by-passing the exhaust check valve or plugged up.

Warlockk

While your checking this both operate from the same vacuum feed. Check the hoses for leaks.