My wife has an 07 ForesterXT and we have replaced the secondary bypass (injection) valve on left bank 2 times and once on the right bank (over about 10K mile intervals). Most of the time they stick CLOSED but one time stuck open and the air pump had to be replaced as well. Ergo… my wife is very familiar with the flashing Cruise and CEL lamp.
The last replacement was just after the warranty expired but the dealer called Subaru and they OK’d it. I have asked for the bad parts but the dealer never seems to provide them for one reason or other.
Just this past month, the code came up (CEL and flashing Cruise) for the right bank CLOSED. She took it in and they want to do both banks (even though the other is OK) and we have to pay the $1000 out of pocket.
From what I can tell these two valves open when the coolant is below operating temp and the air-pump turns on to send O2 in to help the cold Catalytic converter get going. It then shuts off the pump and closes the valves which are solenoid driven with, I presume, a leaf spring check valve in series.
My wife’s 07 XT shuts off the pump after about 20 sec’s max and seems to only run it in the morning. My theory, and I’m sticking with it unless someone has a better idea, is that with one valve stuck closed (normal case after 20 sec warm up from cold start), the air-pump will be OK and we can leave it like this. I continue to check the codes to see if the other valve (third one since bought car) has stuck yet. We will get both replaced when it fails and have the money saved up.
As for cause on only the XT engine, I think it must be the bypass valves location, and water/hot-gas corrosion due to H20 collecting there when parked. If I could hit the values with WD-40 I think they would work again for a few K miles. We live in in western Oregon
Even with the valve stuck, engine runs great and it seems to keep up with my 05 GTO for passing. Can’t find any TSB from Subaru on this but I think there should be.