2000outback Posted November 25, 2006 Share Posted November 25, 2006 For those of you who have been following, my Outback had the CEL on and a code 420 was set.The general consesus was that it might be the front Oxygen sensor.So recently I changed and 2 days later it is back on.Now I haven't had the code read yet so I don't know for sure that it is the same code but that would be my guess.Any suggestions?I know the code actually says it's a CAT problem but I am hoping it's not.What about the rear sensor.What does it do? Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted November 25, 2006 Share Posted November 25, 2006 dtc p0420 - catalyst system efficiency below threshold Do you have any thing like air suction caused by loose or dislocated nuts/bolts, or holes in exhaust pipes? The rear O2 sensor is typically the one used to check the cat(s) for proper/sufficient operation, though the front o2 sensor can cause a condition which would result in that code. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 25, 2006 Share Posted November 25, 2006 For those of you who have been following, my Outback had the CEL on and a code 420 was set.The general consesus was that it might be the front Oxygen sensor.So recently I changed and 2 days later it is back on.Now I haven't had the code read yet so I don't know for sure that it is the same code but that would be my guess.Any suggestions?I know the code actually says it's a CAT problem but I am hoping it's not.What about the rear sensor.What does it do? Where did You get the replacement sensor from? nipper Quote Link to comment Share on other sites More sharing options...
2000outback Posted November 26, 2006 Author Share Posted November 26, 2006 Where did You get the replacement sensor from? nipper It's a Bosch. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 26, 2006 Share Posted November 26, 2006 It's a Bosch. So its not OE ? nipper Quote Link to comment Share on other sites More sharing options...
2000outback Posted November 26, 2006 Author Share Posted November 26, 2006 So its not OE ? nipper No it wasn't OE.Why does that matter? Quote Link to comment Share on other sites More sharing options...
nipper Posted November 26, 2006 Share Posted November 26, 2006 No it wasn't OE.Why does that matter? Yes it does. As its been stated here many times, non OE can be lazy in response giving a trouble code as you are seeing. nipper Quote Link to comment Share on other sites More sharing options...
timintc Posted November 26, 2006 Share Posted November 26, 2006 No it wasn't OE.Why does that matter? ive had an on and off again 420 code going on for about a year now, it comes and goes for seemingly no good reason, tho it did come on once while climbing a grade between marquette and munising with 4 passengers and some hockey gear recently , but other than that one time of being under a full load it just pops up randomly, and sometimes disappears just as randomly, ive read just about every post on the subject and the solutions run the gamut from replacing O2 sensors to replacing the cats, to just doing nothing, as there are no emissions tests in michigan i am content to just monitor my gas mileage, between 23 and 30, and just live with the code popping up now and again, last night i made the check engine light turn off my cycling the ignition 4 times before starting, so i guess if it aint broke ill keep the money in my pocket until such time that it really needs it. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 26, 2006 Share Posted November 26, 2006 ive had an on and off again 420 code going on for about a year now, it comes and goes for seemingly no good reason, tho it did come on once while climbing a grade between marquette and munising with 4 passengers and some hockey gear recently , but other than that one time of being under a full load it just pops up randomly, and sometimes disappears just as randomly, ive read just about every post on the subject and the solutions run the gamut from replacing O2 sensors to replacing the cats, to just doing nothing, as there are no emissions tests in michigan i am content to just monitor my gas mileage, between 23 and 30, and just live with the code popping up now and again, last night i made the check engine light turn off my cycling the ignition 4 times before starting, so i guess if it aint broke ill keep the money in my pocket until such time that it really needs it. It really depends upon the state you live in, if it pops on during an emissions inspection you will fail. Also the check engine light being on may hide another fault triggering the light. nipper Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted November 26, 2006 Share Posted November 26, 2006 It might be the same code, but it is also possible it is not the same code. Getting the code read will at least confirm it is the same code. Quote Link to comment Share on other sites More sharing options...
timintc Posted November 26, 2006 Share Posted November 26, 2006 It might be the same code, but it is also possible it is not the same code. Getting the code read will at least confirm it is the same code. ive had the code read about 3 or 4 times already and i do know what you mean about it possibly being another problem, but i feel that i know my car so well that im not worried too much about that possibility, now if it were running poorly then id have cause for concern. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted November 26, 2006 Share Posted November 26, 2006 Sorry about that timintc I should have specified in my post that I was asking that of the O.P. 2000outback, but yah that isn't fun when all the usual suspect parts have been replaced and the problem just won't go away! Quote Link to comment Share on other sites More sharing options...
2000outback Posted November 27, 2006 Author Share Posted November 27, 2006 I think the first step for me will to have the codes read again to make sure it's the same one.This really bugs me because I had a Neon that had a CEL issue before and it is annoying to look down at the dash and see that orahge glow of that damn light. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted November 27, 2006 Share Posted November 27, 2006 annoying to look down at the dash and see that orahge glow of that damn light.Black electrical tape. Quote Link to comment Share on other sites More sharing options...
hankosolder2 Posted November 28, 2006 Share Posted November 28, 2006 I think the first step for me will to have the codes read again to make sure it's the same one.This really bugs me because I had a Neon that had a CEL issue before and it is annoying to look down at the dash and see that orahge glow of that damn light. I hate to suggest this, but there are "fakeout" oxygen sensor simulator kits which will generate a signal to simulate the output of a rear 02 sensor monitoring a correctly functioning catalytic converter. Some fakeout kits (the really simple ones, using just a diode and a resistor) will cause the OBD2 readout to fail the "readiness" test- but that's of no consequence to you if you don't have to pass an emissions test where the computer is scanned for trouble codes. It will keep the CEL off, but the CEL will come on if another sensor fails or problem develops, which is good. Of course, it's on your conscience whether you feel comfortable driving a car that's polluting more than it should. Good luck! Nathan Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted November 28, 2006 Share Posted November 28, 2006 I hate to suggest this, but there are "fakeout" oxygen sensor simulator kits which will generate a signal to simulate the output of a rear 02 sensor monitoring a correctly functioning catalytic converter. Some fakeout kits (the really simple ones, using just a diode and a resistor) will cause the OBD2 readout to fail the "readiness" test- but that's of no consequence to you if you don't have to pass an emissions test where the computer is scanned for trouble codes. It will keep the CEL off, but the CEL will come on if another sensor fails or problem develops, which is good. Of course, it's on your conscience whether you feel comfortable driving a car that's polluting more than it should. Good luck! Nathan of course if the quality of the o2 sensor is giving you a false reading, you may not be running out of spec. so you need a good sensor. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 28, 2006 Share Posted November 28, 2006 I hate to suggest this, but there are "fakeout" oxygen sensor simulator kits which will generate a signal to simulate the output of a rear 02 sensor monitoring a correctly functioning catalytic converter. Some fakeout kits (the really simple ones, using just a diode and a resistor) will cause the OBD2 readout to fail the "readiness" test- but that's of no consequence to you if you don't have to pass an emissions test where the computer is scanned for trouble codes. It will keep the CEL off, but the CEL will come on if another sensor fails or problem develops, which is good. Of course, it's on your conscience whether you feel comfortable driving a car that's polluting more than it should. Good luck! Nathan fakeout kits are bad in so many ways. o2 sensor is the heart of the fuel injection system. If it is not operating correctly you can suffer poor performance, poor mileage, and worse.. burn up a cat converter. nipper Quote Link to comment Share on other sites More sharing options...
2000outback Posted November 29, 2006 Author Share Posted November 29, 2006 So what I am thinking is I'll just take it to a dealer and have them fix it.Hey Nipper,my question is,should they be able to tell if the that new sensor I installed isn't reacting quick enough or will they just start replacing stuff until the light goes out.I like to be able to sound well informed when I go in so they don't try to screww me over. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted November 29, 2006 Share Posted November 29, 2006 you won't get screwed, just a minimum $300 bill. or a $98 bill with a long list of items that need their immediate attention or your engine will blow up, leave you stranded and be unsafe to drive. Quote Link to comment Share on other sites More sharing options...
2000outback Posted November 29, 2006 Author Share Posted November 29, 2006 you won't get screwed, just a minimum $300 bill. or a $98 bill with a long list of items that need their immediate attention or your engine will blow up, leave you stranded and be unsafe to drive. I know.That's what I am trying to avoid. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 29, 2006 Share Posted November 29, 2006 I hate to state the obvious, but why not replace it yourself? Since you had it replaced recently, the threads should be easy enough to deal with. Or take it to the shop that did it and hand them the OE o2 sensor and tell them to install it. nipper Quote Link to comment Share on other sites More sharing options...
2000outback Posted November 29, 2006 Author Share Posted November 29, 2006 I hate to state the obvious, but why not replace it yourself? Since you had it replaced recently, the threads should be easy enough to deal with. Or take it to the shop that did it and hand them the OE o2 sensor and tell them to install it. nipper I did change it myself and would do it again except they are well over $200 up here in Canada and I would like to know for sure that that would fix the problem.Should a dealership be able to do any tests to determine this? Quote Link to comment Share on other sites More sharing options...
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