charm Posted January 27, 2009 Share Posted January 27, 2009 2000 OBW, man trans, 144k miles After repairing the wiring harness for my vapor recovery canister, I went to clear the code and noticed that there were 2 codes, one the vapor recovery canister, and the other was the dreaded 420. The cats and the front O2 sensor were replaced at about 135k miles. My plan is to blindly replace the rear O2 sensor with a new one with the assumption that it's the only old part that could throw this code. Sound like the right way to go? Or should I take the car to the exhaust shop and let them go through their diagnostics? Thanks a bunch Link to comment Share on other sites More sharing options...
Gloyale Posted January 27, 2009 Share Posted January 27, 2009 Clear it and see if it comes back. this is a code that can show up from a bad batch of gas, other things in the engine wrong, cold cold weather. Did you have a genuine Subaru O2 put in the front? If not htat could be you'r problem. Link to comment Share on other sites More sharing options...
charm Posted January 27, 2009 Author Share Posted January 27, 2009 (edited) It is a genuine Subaru part up front. I have reset the code 2x now. The first time it came back about 4 hours later. The second time it took 24 hours. It's been cold here in Seattle, but not "cold, cold." To me, "cold, cold" is like North Dakota cold. Granted, the car isn't used to this kind of cold. I should also note that both times I reset the code, when I restarted the car, it stalled right after starting. I restarted and went on my way just fine. It's the only two times I can think of that the car has ever stalled on me. I suppose I could also just ride it out and see if it goes away when it warms up a bit. Edited January 27, 2009 by charm needed to add some more Link to comment Share on other sites More sharing options...
Gloyale Posted January 27, 2009 Share Posted January 27, 2009 Sounds like you actually have a "real" issue. I guess at that point I would concur, that the rear 02 should be changed. It would have to be considered the weakest link, if the other stuff is all new. Link to comment Share on other sites More sharing options...
subiemech85 Posted January 27, 2009 Share Posted January 27, 2009 or just 4/20 @ 4:20 replace sensor Link to comment Share on other sites More sharing options...
thermalsurfing1 Posted January 28, 2009 Share Posted January 28, 2009 my 420 reminder light is on all the time Link to comment Share on other sites More sharing options...
charm Posted January 28, 2009 Author Share Posted January 28, 2009 Took it to the guy that did my exhaust. He suggested I fix the minor exhaust leak first. So, I guess I need to run by the dealer and pick up a couple gaskets for the exhaust manifolds! Myabe that'll fix it. Link to comment Share on other sites More sharing options...
fleming442 Posted January 28, 2009 Share Posted January 28, 2009 Also try cleaning the ITS/MAP with throttle plate cleaner. I'm 90% sure it was either that, or the pcv that kept mine off. Similar car/ miles Link to comment Share on other sites More sharing options...
kingbobdole Posted January 28, 2009 Share Posted January 28, 2009 If you have access to a real scan tool you can watch the rear O2 sensor switch... if it follows the front directly, the cat is bad... if it takes forever to change the sensor is bad. It should stay lean 80% of the time. Fix the front exhaust gaskets first... extra air in the exhaust makes the car run richer... which will make the cat seem broken since it cannot clean it up as easy. Link to comment Share on other sites More sharing options...
Gloyale Posted January 28, 2009 Share Posted January 28, 2009 my 420 reminder light is on all the time HBLMAO (hitting b**g laughing my rump roast off) Link to comment Share on other sites More sharing options...
bratman18 Posted January 28, 2009 Share Posted January 28, 2009 my 420 reminder light is on all the time you guys!!!:lol: Link to comment Share on other sites More sharing options...
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