Larry, https://allwheeldriveauto.com/subaru-check-engine-light-code-reader-suggestion/. Buy an O.E. longevity alongside the car’s efficiency and performance. Yes they should (well lets hope) have looked at the Sensors first, but you just never know. Thanks for the info. I’ll stay away from the additive I used and hope it’s back to normal now. Oil pressure warning light added to the BMW E46 330i (MS 42/43) OEM CAN protocol. I have heard that sometimes reflashing the ECU can take care of this P0420 code reflash problem so I am thinking of trying that first. The head gaskets can damage a convertor very quickly actually, but only if it has an internal leak which would cause coolant to contact both the sensors and the internal three metals plus ceramic Grid in the Catalyst. Catalytic Converters are recyclable and just like any other recyclable material including engine oil and coolant is only hazardous if not handled properly. They probably used non subaru gaskets and its possible they didnt do the whole tighten loosen step. Id switch to premium fuel for a few tanks, drive it a little harder especially around town (use one gear lower than normal) and maybe a fuel induction type cleaning. Tim. Because it seems to only show up during the Colder days, Id say its still has some life left, and if it was here that’s what we would suggest. It may very well be that the issue is a weak convertor that is being affected by the colder temperatures only. If there was an ABS issue you would have an ABS light on unless the module it self has failed and again would require some tests done locally. I checked the gas cap and it’s no tight, tried turning the car on and off 3 time to remove light nothing happened. code of P0420. I have a 2005 Subaru Legacy Wagon Limited and I get code P0420. I replaced it when I got home and the CEL went away. My check engine light, ABS, and battery light comes on! I have an 05 Subaru Legacy Outback coming up with a P0420 code. I checked my gas cap but, have not driven it around to see if it resets. The light may go on and off until its resolved. Straight up knowledge from most manufacturers suggests that car They are an independent mechanic (Friend). The running lean code could be a clue as well. Being Memorial Day the only thing I could do myself was tighten the gas cap. Data from any sensor is only as good as the sensor it self! Sorry for the confusion regarding Subaru vs. your independent shop. I don’t want to replace the c.converter if it isn’t broken. it could be worth importing them myself – from what I’ve read online most Subaru ones appear to only be around the $1000 each mark. Symbol Warning Light Description / Action; Airbag: Name: Dodge Journey airbag warning light. I had the converter done at just a regular shop in my area. Any advice as I go chat with them — and likely reach for my wallet? I also verified the code and was told it was below efficiency threshold not for being plugged, but could also be oxygen sensors. After I changed the sensor, that code went away and the P0420 came up. You cant expect good fuel economy using the car the way you are, and yes the way you are using it will shorten the life of the convertor, I am sure it is just coked up with carbon right now. The day after I posted that I came to a sudden stop when a green light turned to red and my Suby violently shook as I came to a stop. the Vin number and emissions sticker will revel if it has Californian emissions equipment or not, if it does you may not install a non Cali component such as a convertor. I also have a k&n drop in air filter too. Thought myself a genius! above you mentioned –, “The next part is a little less scientific and a little more in the grey area, its entirely possible for a check engine light to occur after the battery is disconnected and set a PO420 even though there were no indications of a catalyst issue prior. They also tried to source ECU remap codes that would just “ignore” the reading from the O2 sensors which is how they have solved issues with other models (our emissions laws are not quite as strict as USA or Europe) but because the Tribeca is built in the USA not Japan there is nothing available. At the next stop I popped the hood and noticed a severely leaking battery. The thermostat being stuck open could affect the catalyst function but not the temperature gauge function, it could cause the gauge to read a lower temperature than normal but not cease to function. Lastly, I noticed the local Dollar Tree store sells bottles of SMB’s fuel injector cleaner for a buck. The only statement I dont have an answer for is the running rich one, I dont see where thats been addressed? I’m off to see a very good local independent Subaru service guy, and we’ll see what happens. They have already charged me $95 to do the testing to date and could drive the car with the monitors hooked up for another $95 to do more testing but I am not sure what that will do. Rant over. What to do from here? The engine will die if I don’t put it in neutral and give it gas.Any ideas on what is going on? Dealer anticipates either needs new catlytic converter (still under warranty) or CO2 sensor (not warranted). Then the car will sit in my driveway until he gets back from his trip and he decides on how to proceed. Thanks a lot bud! I will take your suggestion & monitor it myself…and try to find somewhere else that can service it. The check-engine light on my ’05 Outback came on two days ago. There is special intake type cleaner you want to use. I read somebody else had the same issue. Any help or suggestions would be GREATLY appreciated. Try to create some Exhaust heat when driving it and that may help it light of. went on…code po420. The Cruise is disabled with a powertrain code present in the ECM. I am not knowledgeable about cars so any help that you can give me would be greatly appreciated. Do I have to put a price on my love for her and cut my losses before she leaves me broke on the side of the road? I hope this post has helped you? Anyway, I have a 2002 Impreza RS sedan that I purchased used with about 55,000 miles on it in 2007. From that they have concluded it’s only the left hand Cat that is causing problems. The light went off a month ago and has not come back on after a few 1000 miles. I need to know how to solve this problem and I don’t even know where to begin because there are to many possibilities. However, I haven’t seen anything here (or on other sites) yet with my issue. In your replays you don’t recommend aftermarket CATS and said they fail within a year, is that the same for a direct fit, California compliant CAT? He wasn’t sure why the check engine light was coming on and suggested I contact subaru. 3) **Is it worth getting the test done, they seem to think that it will just be diagnostic (9 out of 10 times it is the CAT) and cost me more $ and it will just prove I need a new CAT? I would make the head gasket repairs, then budget for the Subaru convertor when you can and maybe replace the front air fuel sensor and rear oxygen sensor at that time as well. Ageing transmission fluid can easily deteriorate under the extreme heat generated by the transmission itself. If the airbag light no longer comes on, the bulb may be faulty and require replacement. flashing can lead to transmission failure causing the vehicle more damage. – again things were fine (coincidentally? The failed convertor wont do anything to leave you stranded, or do damage by waiting to repair it other than the air quality which is why its there in the first place. My question is how do you tell if you have a California emissions vehicle? Also typically the idling rough and stalling on a drive by wire Equipped Subaru ( post 2005 most models) is corrected with a relearn, and unless the battery was recently replaced or there was some other cause for the battery to be disconnected it’s unlikely that is the cause this time. They CEL is now off and has been for about 4500 miles. All Wheel Drive Auto, LLC and it’s Staff are not affiliated with Subaru of America. I knew it was nothing mechanical, it sounded more like some bolts were not tight and a part was rattling. One year life span for the aftermarket convertors is very typical and very unfortunate which is why we wont use them. My outback is a 2.5i, not an H6, & rust is not an issue. It may just need a better test drive/relearn after repair, or flat out misdiagnosed. https://allwheeldriveauto.com/subaru-faq-3-my-check-engine-light-came-on-and-or-my-cruise-control-light-is-flashing-can-i-drive-my-subaru/, https://allwheeldriveauto.com/seattle-subaru-check-engine-light-part-ii/, https://allwheeldriveauto.com/your-subaru-check-engine-light-explained/. Is that accurate and if it is a new ECM should I ask if it has been calibrated? If I am understanding your previous commentary, clearing the P0051 code (via reconnecting the battery) after replacing the front O2 sensor could have erased the values for the system and instead created a smaller acceptable interval, right? Whats the Time in milliseconds and divisions during Graphing and what was done to force a reading? 106K miles, Had a major engine service about 4 months ago and now check engine light is on. for around 200 miles, and then the code reappeared But so will many other deficiencies in other systems. fact it is a good thing when done properly and at the right time. If so, how? My car is a 2.5 06 Outback with 85,000 miles. Page 157: Low Fuel Warning Light The muffler shop says there are 4 cat conv (2 at engine, two inline mid exhaust). It really helps to have a knowledgable Subaru mechanic give advice like your do. I do not know if that has anything to do with it but, I did add some 50/50 coolant. The P0420 may be related to what ever is causing the P0172, but I cant know that until I diagnosed. fluid has to be changed at frequent intervals to make sure of the component And trust me you don’t want to experience a Transmission It does not seem to be running any different. My dad recommends that I just sell the car, in fear that it may cost us much more than we bargained for. I have a 2003 Subaru Forester with a P0420 trouble code. Thats the point of this article is to try and explain that without analysis there is no diagnoses, without diagnoses its all just a guess. This will be covered by that fund. New or recent doesn’t always mean its ok, it needs to be tested to know if its good. so you think just go for a test will the cat light ofF? Ambient temp vs ECT temp at start up combined with drive time at certain speeds are what ultimately trigger the monitor, when we perform a drive cycle post code clear the catalyst and Evap monitors are the last two to come back online, and sometimes can take days or weeks. i’d really like to stay away from the OEM $400+ part if i could do it for less by just replacing with aftermarket. So at this point all that has been learned is that the ECM is correct and there is a function issue, but until more testing is done we don’t know the why. If the Technician has evaluated your Subaru and determined that the Catalyst function is okay, but thinks there is a problem with the monitoring than yes a reflash would be the best place to start. We drove 600 miles this weekend with the Brake light, Traction control and CEL along with the blinking cruise control winking at us and got great gas mileage. You are still replying to people and seem like a genuine person. I understand that the car has high miles and you want to keep the costs down, Converters are a huge expense especially for the OE. So I had both front bearings replaced. I would start with the higher octane fuel, some driving at higher RPMs at lower speeds and see if you can breath a little more life out of your Catalyst. Thanks, These are obviously aftermarket and he only charged her for the 1st one, about $600. Howdy Justin,Thanks in advance for reading and advice. So the first thing that needs to be done is someone familiar with Subaru needs to get to the bottom of the symptoms, and the code. I would say yes its uncommon to need a second Catalyst at 50k after the first but I don’t know if the front air fuel sensor was ever replaced or if there is something else going on? Your email address will not be published. The premise behind the logic update was to stretch out some of the parameters for when the catalyst function is monitored as in some cases its not truly being tested properly. Throwing the 420 code as well as P0335. In order for the conversion to work efficiently it needs lots of oxygen. I love the advice you give. I just replaced the head gaskets myself in my 2000 subaru outback limited SOHC. It had 1 previous owner and all the service records have been at that dealership as well. When I test with an OBD reader, I get the P0420 code. Thank You. This was a pretty good chunk of change, so I’m sure he was hoping it was good to go for awhile, but now this morning the Check Engine Light came on. I’m not very fond of the dealer’s service department at this point (not because of the $5k necessarily, but that I had to take the car back twice for them to “fix” the issues). “Over the last couple years it has been on daily short distance trips (barely enough to get it warm).Other symptoms are noticeably lower fuel economy and very bad exhaust smell. After driving the vehicle hard for a bit it may go away, but you most likely had a “”on its way out Catalyst” and now that the ECM is merely looking at “pass fail” data in a narrow way its easy to spot the issue. Drove home from work, no problems -15C. So I had both front bearings replaced. Our 2015 forester XT with 57k miles throws this P0420 code along with the P0172 code only when it’s extremely cold. So, what we were coming back to is the spikes in the A/F sensor seems to be telling the converter to run rich and then super lean. -O2 Sensors switching in normal ranges on test drive; air fuel sensors are constant as well This makes the converter more efficient at “oxidizing” HC into H2O and CO2. My thinking is that either the cat has fallen apart or faulty rear O2 sensor. My front CV Boots on both sides need replacing. reservoir, do not drive the vehicle. The car was originally imported from NY and has been in Ontario since (close to 135,000km/84000miles). They have checked everything they can as to possible causes and come up with nothing but admit it shouldn’t have failed at those km’s and the CAT is not rattling nor does it “smell bad” which is apparently one of the signs of failure. To get an OE CAT do I get it from a subaru dealer or is there a place online I can go? If the Catalyst is restricted, in the way of carbon deposits, it wont reach temperature and as such wont function, it is possible in some cases to de-carbon the exhaust system, but only if that is the diagnoses. On a modern vehicle you are asking for trouble if you don’t use a “memory maintainer” tool when disconnecting the battery. You didn’t mention if the Catalyst was replaced with a OE Subaru part or a aftermarket Catalyst? So if you ready, let’s jump into it right now. I’m running 02 Impreza 2.5TS, with EJ251 for about 6 months now. It is a PZEV vehicle sold and driven in Pennsylvania. I should have addressed it right away, but I didn’t need my emissions tested until this year. car fluid at earlier intervals if the car is subjected to any of the subsequent I drive about 60 miles round trip to work, mostly highway, and change the oil every 3k by the book. Like yourself I decided to live with it since it wasn’t imparing my driving. The car continues to run great. kind regards. Without data you dont know if the Catalyst function is improved or not. You could try using higher octane fuel and some spirited driving for a bit and see if that helps it. Is that the next step prior to investing in a new CAT? At one time I had a running to lean code but it has cleared its self.  The why is learned data that has been lost typically with light of parameters, coolant temperature and maybe engine repairs that make changes in Combustion temperature   such as replacing leaking head gaskets. Hi Justin In my case, about a week before the code was tripped, I brought the car to my regular mechanic because we were smelling a fuel leak. CE light came on yesterday. At 75,000 mile maintenance, Dealer replaced head gasket under warranty. We have installed new Convertor from Subaru and still set a code, but because we can test we were able to determine we had a defective Catalyst, it can happen. Its been happening for about 3 years. From what I understood they are only going by OBD diagnostics. Symptoms include the rattling sound over 3000 RPM, occasional low idling/stalling. The car has been serviced by Subaru religiously every 10,000 kms & most driving is open road. Subaru Service: Winterize your Subaru in 2020. I had the code cleared and it came back after a drive cycle. Are there any symptoms to watch for h.g. And if that happened what kind of $ am I then looking at? I appreciate your input. It’s still under one year since I replaced the cat. They reprogrammed the ECM. Of all the vehicle I’ve had over the years with much higher mileage, I’ve never had to replace a converter. of and to in a is that for on ##AT##-##AT## with The are be I this as it we by have not you which will from ( at ) or has an can our European was all : also " - 's your We I like to know before I decide whether High octane fuel has always been used. Is this indicating it is the cat conv at engine end that is reading below threshold.? With age and mileage, I’m trying to fix this cheaply. I’ve wondered if the newer ethynol mixtures contribute to the problem, and if so… what the car makers are doing to correct the issue. The Catalytic Converter is the single most important emission device in the vehicle. Hi, Justin, thank you for info you have provided on this site. Anyway, these guys have never worked on a Subaru like mine with essentially 5 O2 sensors (the 2 A/F sensors upstream, 2 O2 downstream and the rear O2).  You can read about how the system works here. Should it get back to where it was once it’s broken in? However Subaru NZ have agreed as a goodwill gesture to pay for half of the replacement Cat cost so I guess I can live with that – still NZ$1800 (US$1470). How Many Miles Can I Get Out Of My Subaru? On to the good news. The transmission fluid contains grit and debris. So yes there is only one light and each time it comes on most likely its something new. That’s what happens when I post after my bedtime! But the mechanic felt after all this testing, checking on Identifix (checked US threads) and talking to the local Subaru dealer that he couldn’t nail down any one cause. Is this a reasonable thing to do? The car is running fine, no problems. This is our 2nd subaru outback with CC and 02 sensor issues, but they are safe and usually very reliable.