The wife's 99 Outback (100k miles, MT) just popped the "Check Engine" light. Mo OBD II scanner says it's code 141, Downstream O2 sensor heater problem. Looked in the Haynes and it has a photo of the upstream sensor but not the downstream. It also has some minimal troubleshooting checks for voltages and resistance. Anyway, I erased the code and it hasn't come back yet and I'm wondering if this is a common failure (like the EGR) or was it just a spurious reading? I'm a marine diesel mech so I know my way around an engine but I don't know that much about all this emmisions stuff. Any suggestions? How much do these sensors cost? Are they a pain in the rear to get to? Thanks! (Just discovered this forum...it's about time there was a Subaru forum!)