PO402 Vulcan 3.0 OHV

I'd start here...

It's a fault dealing with the EGR valve but doesn't mean the problem is likely with the valve itself.

-bruce snipped-for-privacy@ripco.com

402 means the EGR valve is now stuck open.

Appreciate the links and ideas, guys. Well, a few months ago, I had the manifold off as there were some issues with the pcv valve and removing the manifold was the only way to get to it. Since I had it off, this is the 2nd time the MIL has come on. The first one was a code for one of the O2 sensors and that turned out to be a connection that I forgot to hook back up after replacing the manifold. With this problem, my first thought was maybe a loose or intermittent connection as after all the plastic connectors are now quite brittle with a car this old, so I pulled the connectors leading to the DPFE, cleaned both sides of the connection with contact cleaner spray, than then plugged them closed again. Driving cycle earlier did not cause the MIL to come on, so will now wait and see over the coming days whether it comes back. I understand that this code sometimes needs several driving cycles to appear. Hope not :(

I had PO401 code (insufficient EGR flow), isolated to the DPFE and replaced it Tuesday, drove about 20 minutes total, stopping at 2-3 stores Tuesday night, and the check engine light went off without having to reset via OBD2. Smog check passed on Wednesday with flying colors.