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.