Did your SES light come off after next cold start? or did you have to get the light reset?Thanks xi_ter. The Seafoam did the trick. I've been troubleshooting P1418 SES code for over a year, literally replacing almost every component of the secondary air system, and the Seafoam cleared it in seconds. Many thanks.
I put some seafoam into the hose this morning (just once), and the amount of smoke that came out of the exhaust scared the s#!t outta me!