I'm getting a 0420 error on my 08 Outback, which is probably a sensor on the exhaust system. But the twist is that when it happens, it disables my Cruis Control. The Check Engine light comes on and the Cruise light blinks and is disabled until the code is zero'd out. Then it's fine for a few days or a month but it always comes back. I figured out that the Cruise and Exhauset sensors are on the same system and replaced the main relay for it, but it only lasted a couple weeks then got the error again. Any ideas?