 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Subaru Cars / April 2009Code P0420-Catalyst Efficiency Below Threshhold Bank 1
Got the subject code for check engine light pulled at Auto Zone. Car is a '97 Subaru with 165,000 miles. Could this be the catalytic converter? Auto Zone person said it could be 0xygen sensor. How does on ascertain what the actual problem is? Is the O2 sensor easily accessible on the 2.2l engine? TIA Jim Had the same code on my 95 a few years back. Replacing both sensors has s far solved the problem. Sensors are not easy to get to/remove. Jus unplugging them is a real PITA - Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru More information at http://www.talkaboutautos.com/faq.htm >Got the subject code for check engine light pulled at Auto Zone. >Car is a '97 Subaru with 165,000 miles. > >Could this be the catalytic converter? Auto Zone person said it could >be 0xygen sensor. How does on ascertain what the actual problem is? The Subaru procedure step by step: 1. Check if there are other codes (P0130, P0133, P0136,P0139, P0037, P0301,P0302, P0303, P0304,P1130, P1131, P0031,P0032 and P0038? If yes, investigate those and disregard P0420. If not: 2. Check exhaust system Check for gas leaks or air suction caused by loose or dislocated nuts and bolts, and open hole at exhaust pipes. NOTE: Check the following positions. - Between cylinder head and front exhaust pipe - Between front exhaust pipe and front catalytic converter - Between front catalytic converter and rear catalytic converter If no problems: 3. CHECK REAR CATALYTIC CONVERTER. Separate rear catalytic converter from rear exhaust pipe. Any damage? If not: 4. CHECK FRONT CATALYTIC CONVERTER. Remove front catalytic converter. Any damage? If not: 5. Contact Subaru distributor :-) So unless you have issue elsewhere, things point to a catalytic converter... DK >>Got the subject code for check engine light pulled at Auto Zone. >>Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 36 lines] > >DK Thanks. Will probably put this on hold unil closer to next June when emissions inspection is due again. I seem to recall catalytic converters are quite expensive but one online site has each of them for under $200. Does that not include the platinum stuff? Jim > Thanks. Will probably put this on hold unil closer to next June when > emissions inspection is due again. I seem to recall catalytic > converters are quite expensive but one online site has each of them > for under $200. Does that not include the platinum stuff? > > Jim Aftermarket cats are not a direct fit, they need to be welded to your pipes. Also they typically don't hold up very well. I would encourage you bite the bullet and get your cat(s) from the dealer. >> Thanks. Will probably put this on hold unil closer to next June when >> emissions inspection is due again. I seem to recall catalytic [quoted text clipped - 6 lines] > pipes. Also they typically don't hold up very well. I would encourage > you bite the bullet and get your cat(s) from the dealer. Hi, Certain gas brand works better for certain engine. Here in Canada, I try to avoid Esso brand. > Got the subject code for check engine light pulled at Auto Zone. > Car is a '97 Subaru with 165,000 miles. > > Could this be the catalytic converter? Auto Zone person said it could > be 0xygen sensor. How does on ascertain what the actual problem is? > Is the O2 sensor easily accessible on the 2.2l engine? Amazingly, last week I got this same code on my 01 2.5L. My cat is new as of about 10 months ago. O2 sensor is new too, I believe. I reset the code with my odb-ii scanner, and drove 600 miles and it hasn't returned. I'm holding my breath and hoping at least. -- Todd H. 2001 Legacy Outback Wagon, 2.5L H-4 Chicago, Illinois USA On Jun 23, 12:57 pm, kaplan3j...@example.com wrote: > Got the subject code for check engine light pulled at Auto Zone. > Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 5 lines] > TIA > Jim My son's car has the same code. I did a little research via Google and am going to replace the O2 sensors - they seem to be the culprit at least 50% of the time, according to what I've read on-line. Typically, when a cat 'goes', it breaks up inside and you would get (at least) some rattling and (at worst) a degredation in performance and/or gas mileage as the loose material blocks the flow through the cat. My son's car has neither symptom. Dan D '99 Impreza 2.5 RS Central NJ USA >My son's car has the same code. I have very same code on my 2000 Mazda Protege ES having a hard tine figuring out what it is. Mechanics keeps saying the cat con..... but I'm weary abt that and suspect O2 sensors >>My son's car has the same code. > [quoted text clipped - 3 lines] > keeps saying the cat con..... but I'm weary abt that > and suspect O2 sensors The PO420 code sets when the correlation between the front and rear O2 sensors indicates the cat isn't doing it's job. If one of those two O2 sensors were actually bad instead, it would set a completely different code and not the PO420 code. If your car has more than 120k miles, it wouldn't hurt to replace the O2 sensors. You're going to need them sooner than later anyway. But after clearing the codes you can bet the PO420 code will soon return leading you to replace the cat(s) too. And yes, I am a mechanic. Not just playing one on the internet. ;-) >The PO420 code sets when the correlation between the front and rear O2 >sensors indicates the cat isn't doing it's job. If one of those two O2 [quoted text clipped - 5 lines] >clearing the codes you can bet the PO420 code will soon return leading you >to replace the cat(s) too. Ok thanks so much Dave! I didn't realize al this Sounds like it is in fact the cat con! > On Jun 23, 12:57 pm, kaplan3j...@example.com wrote: >> Got the subject code for check engine light pulled at Auto Zone. [quoted text clipped - 18 lines] > '99 Impreza 2.5 RS > Central NJ USA Hi, Some OBD II scan software can anlyze O2 sensor performance reading the output voltage. Around 2000, there was bad batch of O2 sensors covered by warranty. Believe there is a TSB for this. My kids' 2000 Impreza O2 sensors were replaced during scheduled visit to dealer. So the formal diagnosis is right side has failed and left side is on the edge. All the bolts upstream are tight as new and no leaks. OEM replacement cost including $300 labor is quoted as $1700 for the pair. Any other options that are worth doing? If I was sure nothing else major (like engine or transmission) would crop up in the next 2-3 years it would be a worthwhile investment I suppose but has anyone had any experience with aftermarket or rebuilt ones - which the shop is trying to price as I write this? TIA Jim >Got the subject code for check engine light pulled at Auto Zone. >Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 5 lines] >TIA >Jim >So the formal diagnosis is right side has failed and left side is on >the edge. All the bolts upstream are tight as new and no leaks. Is it the cat con? Or O2 sensors? >>So the formal diagnosis is right side has failed and left side is on >>the edge. All the bolts upstream are tight as new and no leaks. > >Is it the cat con? > >Or O2 sensors? No its the cat con(s). O2 sensors are good. Was first quoted $1400 plus, for parts, for OEM replacement, but now after checking around it's half that. Still a bit more than a grand installed. Does that sound reasonable? >>>So the formal diagnosis is right side has failed and left side is on >>>the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 8 lines] > after checking around it's half that. Still a bit more than a grand > installed. Does that sound reasonable? Unfortunately, yes. They are about 500 buck a pop if you get a good deal. They aren't difficult to install; much like a muffler. But the beasts are expensive. >>>So the formal diagnosis is right side has failed and left side is on >>>the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 8 lines] > after checking around it's half that. Still a bit more than a grand > installed. Does that sound reasonable? How many miles on the converters? Has someone 'scoped' them to see if they are slow switching? (lazy) Has anyone done a flow test through the cat con using the O2 bung? Or even done a sniffer test? I dunno, I've just read of so many people replacing old sensors to get cat con codes to go away - of course, if your sensors are not old and/or you've ever had blown headgaskets or operated the car in a 'rich' condition - then most likely the converter IS bad. I hope whatever shop is doing the work has done good troubleshooting. If the code comes back in a coupla weeks and they want to change the sensor - are they willing to refund the converter charges? Carl  Signatureto reply, change ( .not) to ( .net) >>>>So the formal diagnosis is right side has failed and left side is on >>>>the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 22 lines] > >Carl Carl.. Thanks for your response. The CATS are original - 165,000+ miles. Ditto the 02 sensors. Never blown headgaskets or run the car rich (unless the computer chose to do so). Technician did say that one was just above the pass threshhold, which I assume means he measured something? Not sure if that addresses any of the suggestions in your first paragraph (not being a technician). I can run those by him. Jim >>>>>So the formal diagnosis is right side has failed and left side is on >>>>>the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 34 lines] > > Jim Well, 165K is getting elderly for a lot of components - buthat would be a pretty extreme lifespan for the original sensors I think. many are getting lazy at 80-120K. It comes down to this, it would be better to be wrong about the sensors than wrong about the converter. bya factor of 15-20! personally, I would want to try changing the front O2 sensor (it is exposed to more heat and somewhat more corrosive gasses than the rear one) and clear the codes and wait to see if any return. Start saving your money, and maybe research discount/online dealer prices for the converter (try www.subarugenuineparts.com) and maybe the local dealership will match the price. basically, these two sensors are monitoring the gasses entering and exiting the converter. If readings are outside some limit, they set the code. There is no 'direct' converter measurement so, if an O2 sensor is reading incorrectly - it could throw the very same code, erroneously 'blaming' the converter. Kinda like a person going blind and telling people the lights need replacing! Of course there is a 'heater' circuit that could also fail in the (front I think?) converter. But that doesn't seem to tbe the case here. hey, I'm just some guy that reads a lot on the internet and occasionally tinkers with cars. If you feel the dealership is being up-front about everything and has done the proper testing - then you probably should proceed. good luck Carl Signatureto reply, change ( .not) to ( .net) >>>>>> So the formal diagnosis is right side has failed and left side is on >>>>>> the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 65 lines] > > Carl Try googling some O2 and cat con info. here's coupla sites I found quickly; http://www.gnttype.org/techarea/ecmsensors/O2sensors.html http://www.autohausaz.com/html/emissions-oxygen_sensors.html Carl Signatureto reply, change ( .not) to ( .net) >>>>>>> So the formal diagnosis is right side has failed and left side is on >>>>>>> the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 72 lines] > > Carl another good write-up; http://www.troublecodes.net/articles/catfailure/ Signatureto reply, change ( .not) to ( .net) >>>So the formal diagnosis is right side has failed and left side is on >>>the edge. All the bolts upstream are tight as new and no leaks. [quoted text clipped - 8 lines] > after checking around it's half that. Still a bit more than a grand > installed. Does that sound reasonable? How many miles on the O2 sensors? Has someone 'scoped' them to see if they are slow switching? (lazy) Has anyone done a flow test through the cat con using the O2 bung? Or even done a sniffer test? I dunno, I've just read of so many people replacing old sensors to get cat con codes to go away - of course, if your sensors are not old and/or you've ever had blown headgaskets or operated the car in a 'rich' condition - then most likely the converter IS bad. I hope whatever shop is doing the work has done good troubleshooting. If the code comes back in a coupla weeks and they want to change the sensor - are they willing to refund the converter charges? $80 or so is a lot cheaper than $1400 I'm just sayin'...... ;^) Carl Signatureto reply, change ( .not) to ( .net) >>Is it the cat con? >> [quoted text clipped - 5 lines] >after checking around it's half that. Still a bit more than a grand >installed. Does that sound reasonable? Ouch! Damn them things are pricey! >Got the subject code for check engine light pulled at Auto Zone. >Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 5 lines] >TIA >Jim 500 miles after replacing the two cat cons, the code came back. Shop exmaine everything and crimped a couple connections they said might have a tiny air leak. 500 miles later code came back and now I am being told the front 02 sensor is definitely failing. They did say they went through fairly exhaustive checks (as detailed elswhere in this forum) to ensure the origina problem was the cat cons. Here's the new wrinkle: today the alternator failed (suddenly it seemed). After replacing the alternator and 8 year old battery, the CEL is not on, but I'm assuming it will come back on. Unless...is there some possibility of the code having been set my a malfunction due to erratic voltage from a failing alternator? TIA Jim >>Got the subject code for check engine light pulled at Auto Zone. >>Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 11 lines] > being told the front 02 sensor is definitely failing. They did say > they went through fairly exhaustive checks oh that was a terrible joke. (I loved it) > (as detailed elswhere in > this forum) to ensure the origina problem was the cat cons. [quoted text clipped - 4 lines] > there some possibility of the code having been set my a malfunction > due to erratic voltage from a failing alternator? I'm fighting with this code too, and have no insight for ya. It seems the "mechanic" I had who supposedly replaced my cat either didn't, or replaced it with a used cat. At any rate, there's a big hole in my cat that explains the code, and welding it up hasn't seemed to solve it, unfortunately. The front o2 was replaced earlier. Sorry I don't have any answers, but I can comiserate. Now when I reset the code it goes away for about 80 miles, but then comes back. -- Todd H. 2001 Legacy Outback Wagon, 2.5L H-4 Chicago, Illinois USA >>Got the subject code for check engine light pulled at Auto Zone. >>Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 21 lines] >TIA >Jim The saga continues. NEw 02 sensors eliminated the CEL for a few hundred miles and a second set of catalytic converters for 1200 miles but now it is back, same code as ever. The cat cons are not Subaru OEM, but do have an 8 yr/50,000 mile warranty and were $600 less than Subaru ones. Any other more offbeat ideas of what's going on here? TIA Jim >>> Got the subject code for check engine light pulled at Auto Zone. >>> Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 31 lines] > TIA > Jim There are diagnostic tests. A scope will indicate to a competent technician if the sensors are switching fast enough with the proper out put voltage. tailpipe gas sniffers should tell a tech what's up with the converters. A coupla other ideas - bad ground or other electrical connection. bad/intermittent ECU. Carl >>>> Got the subject code for check engine light pulled at Auto Zone. >>>> Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 39 lines] > >Carl This is getting pretty frustrating. I'm sure it would be at least as much so if I were actually a DIY person. I know they scoped the O2 sensors both prior to replacing the front one (just checked the service record and only the front one has been replaced) and after replacement when the CEL came on again (and they were responding properly), I assume they did a sniff test (this is a state recommended emission repair facility) and I have repeatedly since the initial cat replacement) mentioned my concern about electrical and computer issues. I suppose now they could tell me it's the rear O2 sensor. But I have no plans to replace anything further until after the car fails the state emission test in a couple months (they just read the codes, no actual tailpipe test) because I want any further expenditures credited toward a waiver if one is required. I'm environmentally concerned, but not convinced there's a real emissions issue (see last sentence of Carl's post above) >>>>> Got the subject code for check engine light pulled at Auto Zone. >>>>> Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 58 lines] >not convinced there's a real emissions issue (see last sentence of >Carl's post above) The next step is going to be Subaru cats, but given that the shop says they have had no problem with the supplier/mfr of the ones they used first and still on my car, I have a sneaking feeling this will not put an end to this continuing saga. I hope I am wrong. On Feb 6, 11:24 pm, kaplan3j...@example.com wrote: > >>Got the subject code for check engine light pulled at Auto Zone. > >>Car is a '97 Subaru with 165,000 miles. [quoted text clipped - 34 lines] > > - Show quoted text - I propose that perhaps your car is just messing with you. When my car does this, I just smack it hard. It never helps though... But seriously. I have the same code, and am hoping it is the O2 sensor. I have a 95, and the rear O2 sensor is on the rear cat. I tried to get it out for about 45 minutes this weekend with no luck. It's hard to get enough torque on it to bust it loose. It seems that one of two things always happens, I have the wrench lines up correctly so that it holds, but then the damn sensor won't rotate, or I have it off a little and it just slips, slowly rounding the hex part of the sensor. I tried a plumbers wrench, but couldn't get it in there. I also tried some PB'laster, which usually loosens rusted on crap pretty well. I also tried running the car to heat up the cat. None of this worked. Any ideas? I've considered a torch on the cat close to the bung for the sensor, but dont[ know how smart that is. I don't know how much heat it can take. Any better ideas? I could just take it to a shop, but I feel silly takign my car to a shop to have them unscrew something, and screw another right in. Bill >On Feb 6, 11:24 pm, kaplan3j...@example.com wrote: >> [quoted text clipped - 58 lines] > >Bill Check engine light has gone out for a week or so. Burned out, or problem solved itself, or more likely, car messing with me... >>On Feb 6, 11:24 pm, kaplan3j...@example.com wrote: >>> [quoted text clipped - 61 lines] > Check engine light has gone out for a week or so. Burned out, or > problem solved itself, or more likely, car messing with me... If it makes you feel any better, I haven't done anything to mine, and it's coming and going with that code. I know I have a small hole in that cat though, according to the mechanic. Which of course is irritating because I'd paid a mechanice (who's since fled to Mexico) for a new cat about a year ago. Seems maybe that brand of gasoline makes some sort of difference, but I can't say exactly how. The rubber will meet the road here soon though--emissions testing flyer came in the mail last week. LOL. -- Todd H. 2001 Legacy Outback Wagon, 2.5L H-4 Chicago, Illinois USA >>>On Feb 6, 11:24 pm, kaplan3j...@example.com wrote: >>>> [quoted text clipped - 73 lines] >The rubber will meet the road here soon though--emissions testing >flyer came in the mail last week. LOL. I think my emissions test invite is due any day now too. Last done in June of 2007. >On Feb 6, 11:24 pm, kaplan3j...@example.com wrote: >> [quoted text clipped - 58 lines] > >Bill Car continues to mess with me. CEL light was on, then off for 750 miles or so, and is now back on. Proposal is to return the aftermarket cats and replace with Subaru ones. But I do wonder about one thing. When the CEL came on again after being off,, I took the car in to have the ECU scanned. While code P0420 remains in memory, according to the shop, the car was listed as currently passing all tests (my paraphrase of what he said). So although the shop insists the ECU itself cannot be an issue, I wonder if the CEL light on but "currently passing all tests" make sense. I know it can go off by itself after coming on from the P0420 code. Jim My 2 cents. Subaru implemented a program last year to help the Subaru tech ACCURATELY diagnose the p0420 code. It seems as tho Subaru Warranty was replacing too many of them that were not defective. Unfortunately, the test requires a scan tool that can graph live data and are watching for specific reactions between the ft AF ratio sensor (or o2 sensor in older vehicles) and the rear sensor. It requires driving at specific speeds and letting off on the throttle to trigger a response. Having worked in the aftermarket world, I do not support the use of aftermarket o2 sensors and cats. On my dad's own truck, the aftermarket o2 sensor didn't work correctly and required a ford OEM sensor to cure the issue. Aftermarket cats often do not fit correctly (Mom's car caught fire right after she traded it in - I had nothing to do with that!) or don't quite work correctly. The data is in a pdf format on the shops laptop/scantool, and I cannot seem to be able to transfere it to show you. I will try to transfere some of the important parts of it soon. Hi Jim, All! >Car continues to mess with me. I fixed this issue on a late 90s Legacy by swapping out the entire Y-pipe/CAT/O2 sensor assembly with one from a wrecked car. Technically, I don't think the salvage yards are supposed to resell emission control hardware, but if you ask nicely, and ask for a "Y-pipe" or "Front exhaust pipe" rather than a "CAT and O2 sensor", you'll probably be able to land one. It's been awhile, but I seem to remember spending $150 for the assembly. Hope this helps. ByeBye! S. Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101 |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.