Just got the following from my Subaru service mgr. who had been tracking down the cause of CEL and resulting unusual code P2097 on my
05 OB 2.5i.
Apparently this is a problem known by Subaru even though there has been no TSB or recall - yet. It is also associated with some kind of engine surging while running on Cruise Control.
The solution: Have the service shop plug in their reader and get the ECM calibration ID#.
They can then send for the appropriate cartridge from Subaru and reflash the ECM firmware which takes about 1/2 hour.