SubeeTed Posted July 18, 2016 Share Posted July 18, 2016 Hi ALL ! I've got the dreaded PO420 code. CAT below threshold ..... ! I have a 2005 Legacy Wgn i, Auto. It runs just fine, gas mileage is fine ! IT IS A CALIFORNIA Emissions car !! I want to replace the last 02 sensor, OEM part # 22690AA45C. I can get it for $130. I've heard that they are made by DENSO, I've found this DENSO site . The 02's they have are much less, but ARE they really the real thing ? IS this what SUBEE uses ? WE DENSO #'s are DEN 234-4732 or DEN 234-4446. Or am I just hoping and this is a waste of time ????!!! Many thanks, Ted Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted July 18, 2016 Share Posted July 18, 2016 P0420 is a tough code to troubleshoot. On an older car - you'd definitely want to confirm there's no exhaust leaks or overlooked maintenance/tune-up type of problems before spending $100s of dollars on sensors or cat convs. Quote Link to comment Share on other sites More sharing options...
montana tom Posted July 18, 2016 Share Posted July 18, 2016 Denso is the oem manufacturer , do yourself a favor and look on rock auto parts for your o/2 they have much more reasonable prices on name brand parts. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted July 18, 2016 Share Posted July 18, 2016 It can be tricky to get rid of; people try various things. I had it on my '00obw but never got rid of it. I replaced the rear, then front sensors, with the genuine part, but the code would still come back. I would get the code only on really windy days. Make sure all your heat shields are in place is something others have mentioned. Since mine would only pop infrequently (when really windy every couple months) I just reset it, and normally at inspection time it was ok because I hadn't reset it recently. One thing I've seen mentioned is a spark plug non-fouler. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted July 18, 2016 Share Posted July 18, 2016 For what it is worth, I replaced the front (upstream) 02 sensor with a Bosch sensor on my 99 OBW. I bought it from Advance Auto Parts on line. Listed for $78, with coupon discount, price was $54. It works just fine. Car runs great, and no check engine light coming on. Quote Link to comment Share on other sites More sharing options...
SubeeTed Posted July 18, 2016 Author Share Posted July 18, 2016 (edited) I was goining to go with rockauto. They are about one dollar cheaper each than the other site. One goes for $46 the other $51 . And they have other stuff I need. It will be the first time I've tried rockauto, only here good things about them ! It sounds like what I already know....there are NO absolute solutions for this situation! So I'll do the cheaper thing first.....and HOPE !! Edited July 18, 2016 by SubeeTed Quote Link to comment Share on other sites More sharing options...
somick Posted July 18, 2016 Share Posted July 18, 2016 roach auto data base is very inaccurate! Beware. They will stick you with a wrong part and you will be responsible for shipping it back. Try Amazon. Good luck, Sam Quote Link to comment Share on other sites More sharing options...
somick Posted July 18, 2016 Share Posted July 18, 2016 Have you tried the anti fouler before replacing the sensor? 1 Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted July 18, 2016 Share Posted July 18, 2016 (edited) RockAuto is best if you get several items from the same warehouse. And make certain the part has a US flag - sometimes parts are for European model cars. I've had about the same amount of disappointment from RA as Amz - and very, very little over-all from either. Advance Auto sometimes has good rebates for first-time users of their on-line site. Edited July 18, 2016 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
montana tom Posted July 18, 2016 Share Posted July 18, 2016 As somic said rock auto can send wrong parts. Look closely at your original connector ,compare it to the picture of the new one, if the connectors match you will be ok. I bought one for my 2000 obw recently... no problem with fitment, even got the cel to go off... 3 weeks later its back on, same code. Thank goodness montana does not have emission testing . Quote Link to comment Share on other sites More sharing options...
SubeeTed Posted July 18, 2016 Author Share Posted July 18, 2016 Anti Fouler ? What would that be ? If you mean Cataclean....YES , I did that no results ! So it seams the jury is out on who to buy from !! RA or Amazon !!! I knew this wouldn't be simple.......!!! Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted July 18, 2016 Share Posted July 18, 2016 (edited) sometimes you pay local taxes from Amz, never did that from RA (yet) I've bought from both and been very satisfied. Look on-line for a 5% off code for RA. I will say, Amazon has a dead simple return procedure that works very well, most of the time, if something is wrong with the order. Edited July 18, 2016 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
DaveT Posted July 18, 2016 Share Posted July 18, 2016 Do be sure to check for a leak. It doesn't take a big one to cause that code to show up. Quote Link to comment Share on other sites More sharing options...
brus brother Posted July 19, 2016 Share Posted July 19, 2016 (edited) Anti Fouler ? What would that be ? If you mean Cataclean....YES , I did that no results ! So it seams the jury is out on who to buy from !! RA or Amazon !!! I knew this wouldn't be simple.......!!! you'll need to drill these out but: antifouler from autozone orf wm http://www.walmart.com/ip/Dorman-42009-Spark-Plug-Non-Fouler-18mm-Gasket-Seat-Pack-of-2/191881703?wmlspartner=wlpa&selectedSellerId=371&adid=22222222227040538595&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=99532280554&wl4=pla-234123911074&wl5=9003369&wl6=&wl7=&wl8=&wl9=pla&wl10=111839980&wl11=online&wl12=191881703&wl13=&veh=sem search google and there are some sellers that drill them out for you for a little more $ That being said: This DID NOT WORK on my 05 OB. Something about the way the computer reads info on 05+ models. Just our luck huh?! I bought a cheap code reader for about $20 and for the past 5 years, I clear the code so as to pass inspections and away I go. Never found a leak, never found a cause. Never found that it affects performance other than disabling cruise control and the light show of blinkers in the dash cluster. Edited July 19, 2016 by brus brother Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 19, 2016 Share Posted July 19, 2016 2005's have some ECU/converter related recalls/updates - i would check and make sure you don't need to reflash your computer which they did to 2005's. 05+ i don't think the spacers will work in 2005+ due to significant changes in how the ECU and O2 data are intergrated (before 2005 it was just a trigger circuit, very simple, didn't really do anything). where you buy doesn't matter - just pick one. Quote Link to comment Share on other sites More sharing options...
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