August 18, 200916 yr I thought I'd start another thread for this so that things start fresh. As a result, here's the vitals... 2000 OBW 2.5 auto 158k miles. New front o2 sensor last week. New cats a few weeks ago. New rear 02 sensor about 2 months ago. Car runs smooth, gas mileage is currently the best I've ever seen. Head gaskets replaced along with timing belt and every engine seal at 125k. New plugs and wires, air filter, fuel filter and sea foamed just before the cats were replaced. No other codes besides P0420. Guesses? What do I look to next? I can't replace anything else in the P0420 stream can I?
August 18, 200916 yr Author Oh yeah. It was cleared after the latest O2 sensor was installed. It was good for 4 days or about 250 miles. Prior to that, the code had been cleared and came back after a day. Same thing the previous time. The time prior to that it was about 2 weeks. The same 2 weeks that followed the replacement of the cats.
September 2, 200916 yr I have been chasing P0420 for a couple of years on my 00 OBW. New O2 sensors etc. If I cleared the code it would usually be ok for a week or so. Then it would start being on for a few days, off for some short period then back on and so on. Never off for more than a week over the last 2 years. At the end of July I was cleaning up the engine compartment and disconnected the battery for a couple of hours. Haven't had P0420 since then which is nearly 5 weeks now. Easy to do, might be worth a try.
September 2, 200916 yr Believe it or not, but research I did on this issue suggests that fuel pressure, either a drop in or continuously low (as in not where it should be) could be a cause. I suspect the SeaFoam treatment may have had something to do with it, maybe not. At any rate, try the old battery disconnect for a few minutes and see what happens as already suggested. Here's the link if permissable to the link: http://www.automotiveforums.com/t667072.html
September 3, 200916 yr This will fix your CEL code P0420 - Catalyst System Efficiency Below Threshold problem. 1.Go to your local auto parts store and buy this: 2. With a 1/2" drill bit, bore out only ONE of the anti-foulers in order to accommodate the size of the o2 sensor head. Screw in your o2 sensor into the bored out anti-fouler then screw that into the other untouched anti-fouler and voila! Here is a pic with this setup: Stole this tip from the Wild World Web.
September 7, 200916 yr This will fix your CEL code P0420 - Catalyst System Efficiency Below Threshold problem. 1.Go to your local auto parts store and buy this: 2. With a 1/2" drill bit, bore out only ONE of the anti-foulers in order to accommodate the size of the o2 sensor head. Screw in your o2 sensor into the bored out anti-fouler then screw that into the other untouched anti-fouler and voila! Here is a pic with this setup: Stole this tip from the Wild World Web. ******************** here's my question You mean bore out the 1st one AND THEN re-tap some threads in it...correct?? If 420 cel is always on...isn;t it possible your gas mileage will suffer? Could there be any other neatives to doing this? anyone? thanks
September 8, 200916 yr ********************here's my question You mean bore out the 1st one AND THEN re-tap some threads in it...correct?? If 420 cel is always on...isn;t it possible your gas mileage will suffer? Could there be any other neatives to doing this? anyone? thanks I know that some of you know the answer to this,....I don't really want to spend $100.76 plus shipping to get an OEM o2 sensor for my sons 96 legacy if I don't have to....what do you guys think? thanks
September 8, 200916 yr try PMing or emailing the person with a link to this thread and ask them to clarify. or search the internet, looks like this has probably been addressed on other sites. subaruoutback or legacy forums i bet has some info. let us know if you find anything.
September 8, 200916 yr try PMing or emailing the person with a link to this thread and ask them to clarify. or search the internet, looks like this has probably been addressed on other sites. subaruoutback or legacy forums i bet has some info. let us know if you find anything. Gary I hear you...but I should have clarified ....I am more interested in the effect of bypassing the 0420 code being thrown...what are the potential downsides?
September 10, 200916 yr GaryI hear you...but I should have clarified ....I am more interested in the effect of bypassing the 0420 code being thrown...what are the potential downsides? Now guys...I have a hard time believing that no one knows the answer to the above (previous) post.... anyone?? thanks
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