Re: Dreaded P0505 has me in it's grasps!
What I found on my coupe's RCM is the contacts on the relay that controls the air pump are badly burnt. (pic later)
I haven't changed out any gaskets and checked all connections when the code first appeared. I cleared the code and I say a month or so later it reappeared. Thinking perhaps the relay isn't always making good contact thus not turning on the air pump then throwing a code.
One of these days I'll get a burnishing tool and clean the contacts, clear the code and see if it comes back.
Might swap RCM to the roadster and see if the fault follows.
Thoughts?