I've got an EJ207 with a protune, with about 12,000 trouble-free miles on the engine. Of course, as a used JDM motor it wasn't new when it was installed.
Started to get a temporary solid CEL on hot restart that went away once I drove away.
Grabbed a universal code reader and it looks like from the codes - see pictures below - that it's the rear O2 sensor. I replaced the front O2 sensor and the timing belt when we put the motor in.
Not sure why I'd be getting a cam position sensor code as well, because the timing belt was replaced at installation with this motor as well, but what do you think?
Oh yes, here is the code reference: http://www.autocodes.com/p0365_subaru.html