I am original owner of 2005 Subaru legacy i (4 cylinder) automatic trans. Has 198,000 miles, have done all the required maintenance at the Subaru dealer, including new head gasket @ 161,000 and new catalytic converter at 172,000. For the last 3,000 miles I have a non blinking CEL blinking cruise control with a code of PO457. I have replaced gas cap 3 times, with last time using original Subaru cap. Have had to dealer three times. They have even done the "smoke test". I own a code reader, which lets me reset and turn off CEL. It stays off for 180 to 230 miles, then comes back on. Dealer is puzzled, but willing to take my money to continue testing. Other than not having my cruise control, there seems to be no effect on performance or gas millage. Any ideas what this could be? If I just continue to reset the CEL every 200 mile or so, am I risking something going seriously bad with the engine. I love this car otherwise. It is good shape, no rust, interior very decent condition.
Have had to dealer three times.
Stay away from the dealer and find a good independent mechanic who can diagnose the problem. A vacuum test and checking purge valve operation may reveal more than the smoke test.
https://eeuroparts.com/blog/p0457-code-causes-fixes-and-more/
" find a good independent mechanic" - that is the tricky part, isn't it!
Unfortunately, yes. We have a few referrals in the FAQ but they only cover very limited areas.