Subaru p0420

I've read on the forum that the p0420 code is a cat replacement. I brought this up to them earlier today and they wanted to do the spark plug replacement. I plan to call them tomorrow but wanted to get your all's thoughts/advice. Should I contact Subaru of America tomorrow as well?

P0303 and P0304 are misfires on cylinder 3 and 4 (the rear cylinders). P0420 is a cat efficiency code caused by the misfires, too much unburnt fuel going through the exhaust. Check the spark plugs (especially the gap), wires, and ignition coil. It could also be a problem with the fuel injectors.Nov 21, 2023 · P0420 Code Chasing - Graph of O2 Sensor. Hi all, I've been chasing a P0420 code on my base 2007 outback (to prevent the CEL from coming on so my cruise will work). Check engine light first came on with P0420 after about a hundred miles. I reset the code, and after about 60 miles I saw the code "pending" again though it wasn't confirmed and no ... The P0420 Diagnostic Trouble Code is a clear indication that your vehicle's catalytic converter is not efficiently functioning. The Catalytic Converter is part of the …The numbers: Ugly, as expected. Credit Suisse reported a second-quarter loss of 700 million Swiss francs ($779 million), its worst quarterly result since the depths of the financia...P0420 data interpretation, 2007 2.5 non-turbo. Hi all! Ive collecred some data and am hoping someone can help me figure out my next step. I have a 2007 outback. 2.5i. 200,000km. A few weeks ago, the coil burnt out and I lost cylinder 3&4. I drove about 5km home hoping to avoid a late night tow bill.The P0420 engine code indicates the catalyst system efficiency is below the threshold (Bank 1). A P0420 code indicates a problem with the catalytic converter, more specifically. The purpose of the catalytic converter is to break down harmful pollutants created during the combustion cycle. By using fine platinum and gold meshes to filter exhaust ...We did a comparison to help you save as much as possible when shipping a package. Here are the cheapest ways to ship a package! Home Save Money Do you have a small business with a...

Causing bad readings which throws a code telling you that you need a new cat or O2 sensor. Start up front and move your way to the exhaust. Hey Tyler, air filter is stock, I haven’t changed it yet, I’ll check right when I get off work. 11-16-2017, 10:15 AM. # 6. gn4rwhals vbmenu_register ("postmenu_45422896", true);Subaru’s Lineartronic CVT design uses a chain rather than a cable to join the two pulleys of the CVT system as in most other CVT designs.How to diagnose code P0420 on a Subaru Legacy. Typically, you'll find out about P0420 because your malfunction indicator lamp or "check engine light" turned on & you or a mechanic diagnosed the problem with an OBD II code scanner like this one from Bluedriver. You may experience a very slight reduction in engine power from reduced exhaust flow ...Mar 13, 2023 · OBD II fault code P0420 is a generic code that is defined as “Catalyst System Efficiency Below Threshold (Bank 1)”, and is set when the PCM (Powertrain Control Module) detects a condition that indicates that the catalytic converter on Bank 1 is operating below the minimum allowable efficiency threshold. Note that on engines with two banks ... P0420 data interpretation, 2007 2.5 non-turbo. Hi all! Ive collecred some data and am hoping someone can help me figure out my next step. I have a 2007 outback. 2.5i. 200,000km. A few weeks ago, the coil burnt out and I lost cylinder 3&4. I drove about 5km home hoping to avoid a late night tow bill.p0420 maybe a rear o2 sensor at this stage,...although other things produce it such as a a loose exhaust gasket before the last o2 sensor. p0442 and p0456 both indicate of a minor evaporative system leak,...such maybe a hose or something in the area of the gas tank and the attached evap system that has become cracked overtime. be it a …2009 - P0600 and P0420 - Updated! 2009 2.5 4EAT, Premium, 135000 miles. Ive been getting a P0420 for the last year. Even after a new exhaust was installed, including new sensors. Sadly, for me, I just reset the code each time it occurs as the car generally runs "OK". I drive about 70 miles each day (35 miles each way) for a commute …The most common fix for P0420 in the Subaru Baja is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Baja into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru Baja: 1. Check for Other Codes.

The Continental ContiProContact tire is the best overall tire for the 2015 Subaru Forester as of March 2015, according to tire review site BestReviews.com. The site also recommends...This code simply means that somewhere in the chain of events that controls the overall performance of the engine there is a problem and you have to find it. List of …J. Jdave Discussion starter. 7 posts · Joined 2017. #11 · Sep 11, 2019. A code P0420 may mean that one or more of the following has happened: Leaded fuel was used where unleaded was called for (unlikely) A damaged or failed oxygen / O2 sensor Downstream oxygen sensor (HO2S) wiring damaged or connected improperly.If the check engine light comes on in your Subaru there is always a corresponding code set in the computers memory. You can read about how the system works here. Subaru Check Engine Light Part 1. Subaru Check Engine Light Part 2. One of the more common codes we see on the Subaru, is P0420 Catalytic Converter Efficiency Below Threshold.

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This code simply means that somewhere in the chain of events that controls the overall performance of the engine there is a problem and you have to find it. List of …Code P0420 Description. The Engine Control Module (ECM) uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency. The first sensor, the air-fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to …P0420 Hard to start Help! 2002 Forester L. 136k Manual transmission. Bought this car about a month ago (first subaru) about a week into owning the car it developed a small intermittent start issue. Basically when the engine is WARM it will crank 2-3 times then misfire. Turning the key off then back on it almost always cranks once and …104 posts · Joined 2008. #2 · Oct 3, 2011. I as well have been dealing with the P0420 and a local subie dealer out here mentioned basically to clear the code and see how long it takes for it to come back up. Meanwhile, run fuel cleaner through the system to clear up the injectors and the 02 sensors. You said your putting the anti-foulers on ...This Subaru Outback has a P0420 Again! This catalytic converter was replaced two and a half years ago and the light is on again for catalytic converter ineff...Oct 19, 2015 · Every mechanic has seen intermittent P0420's that come back after months or a year, that's common. A P0420 due to an oil filter is unheard of. More than likely the P0420 was intermittent and was going to go out and come back at some point no matter what you did. H6 OBW VDC, H6 OB Sedan, Tribeca, Lifted XT6. traildogck.

P0420 data interpretation, 2007 2.5 non-turbo. Hi all! Ive collecred some data and am hoping someone can help me figure out my next step. I have a 2007 outback. 2.5i. 200,000km. A few weeks ago, the coil burnt out and I lost cylinder 3&4. I drove about 5km home hoping to avoid a late night tow bill.P0420 is catalyst below efficiency. P0303 is misfire on cylinder 3. The misfire could be contributing to the catalyst problem so it should be addressed first. Pull the # 3 plug and look for carbon or wet with gas. The old plug wires are also suspect. Clean the plug and re-install. Check the connections on both ends of the wire.The P0420 engine code indicates the catalyst system efficiency is below the threshold (Bank 1). A P0420 code indicates a problem with the catalytic converter, more specifically. The purpose of the catalytic converter is to break down harmful pollutants created during the combustion cycle. By using fine platinum and gold meshes to filter exhaust ...5784 posts · Joined 2018. #2 · Apr 12, 2023. There is a whole thread on this forum about the P0420 code, what can cause it and how to diagnose the cause. If you take the time to read the first 10 to 20 posts of that thread you may be able to diagnose the cause. The code can be caused by bad fuel, faulty O2 sensors, poor electrical …2012 Forester 2.5X Manual 5spd - 142,309 miles. I bought the car in July 2021 with 116,000 miles. About 8/10 months ago or so, a P0420 code popped up, I did nothing about it for awhile since the car seemed to be running fine. Then a few months ago the car stalled as I was exiting the highway approaching the stop light at the end of the exit ramp.In this video, we're going to show you a quick and easy way to fix your P0420 without having to replace your catalytic converter. This is a quick and easy fi...Apr 9, 2017 · If you've cleaned your MAP, then all that's left is the rear O2 sensor and the cat itself. Dealers change rear O2 sensors . . . mostly because that's one of the few pieces left in the puzzle. Then comes the cat . . . chi-ching! Honestly, I think Subaru uses the P0420 to increase dealer repair traffic. P0420 data interpretation, 2007 2.5 non-turbo. Hi all! Ive collecred some data and am hoping someone can help me figure out my next step. I have a 2007 outback. 2.5i. 200,000km. A few weeks ago, the coil burnt out and I lost cylinder 3&4. I drove about 5km home hoping to avoid a late night tow bill.If you've cleaned your MAP, then all that's left is the rear O2 sensor and the cat itself. Dealers change rear O2 sensors . . . mostly because that's one of the few pieces left in the puzzle. Then comes the cat . . . chi-ching! Honestly, I think Subaru uses the P0420 to increase dealer repair traffic.If you find a P0420 code in your Subaru or Honda, it’s most likely the catalytic converter to blame. It can also be caused by an …

May 11, 2017 · So my wife and I bought an '07 Outback Basic back in January, used with about 130k miles on it. MIL came on around 6 weeks ago with a P0420 code. Been doing a lot of googling/reading about P0420 codes lately- I've had several conversations with different mechanics around town, some helpful and some not, but someone suggested that since the only ...

How to diagnose code P0420 on a Subaru Outback. Typically, you'll find out about P0420 because your malfunction indicator lamp or "check engine light" turned on & you or a mechanic diagnosed the problem with an OBD II code scanner like this one from Bluedriver. You may experience a very slight reduction in engine power from reduced exhaust flow ...This will fix a P0420 code most, if not all of the time. Also have a look at this thread: $5 fix ~ Silke ~ '02 Forester S 5MT - "Cooper" '11 Honda CR-Z 6MT - "Kat" ... We’re the best Subaru Forester Owners Forum to talk about the best years of the Subaru Forester, modifications and reliability history of the Subaru Forester.21417 posts · Joined 2006. #5 · Jul 10, 2014. However, when the light is cleared, while using the cruise control there is a slight hesitation present ONLY while the cruise is being used. There is no hesitation or issue present otherwise. It's possible that the P0420 and the hesitation are related, and that the hesitation is more noticeable ...French prosecutors are looking into claims the Bolloré Group offered cheap communications services to the presidents of Togo and Guinea in exchange for contracts. France is investi...Jan 29, 2024 · The P0420 code in a Subaru Outback is typically triggered by issues related to the vehicle’s catalytic converter. One common cause is a faulty or damaged catalytic converter, which may be clogged or no longer functioning properly. Another possible cause is an oxygen sensor failure, specifically the downstream oxygen sensor, which measures the ... That's one of Subaru's plans to make you fix your car instead of ignoring the code. In my experience the P0420 code has always been fixed (4 times on three different cars, and the second time on one car was the other bank on a 3.6R) by replacing the downstream O2 sensor. Did you replace it with a good brand-name sensor or whatever …May 23, 2011 · P0420 is VERY RARELY a failing cat. It is most commonly a failing oxygen sensor (front Subaru, rear any brand), vacuum leak, exhaust leak or what not. Search that code on the forums and you'll find plenty of info. Cats rarely fail without serious mechanical problems, I think your mechanic wants to give you an expensive repair bill. P0420 is VERY RARELY a failing cat. It is most commonly a failing oxygen sensor (front Subaru, rear any brand), vacuum leak, exhaust leak or what not. Search that code on the forums and you'll find plenty of info. Cats rarely fail without serious mechanical problems, I think your mechanic wants to give you an expensive repair bill.Subaru code P0420 refers to a diagnostic trouble code that indicates an issue with the catalytic converter efficiency in the vehicle’s exhaust system. This code …There is a lot of info out there on this subject but none seemed to be specific to an intermittent power loss issue with P0420. I understood one sensor should fluctuate rapidly (upstream) and the other should remain fairly steady. If I recall correctly, the fluctuation was between about .04-.80.

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Subaru Mechanic: Mike Alberghini. Hello! P0420 is referring t the exhaust system. it could be something like an exhaust leak, bad oxygen sensor, or bad catalytic converter. The other 2 codes are not real codes, and are due to your scan tool not knowing how to read the codes given to it by the computer.As u/oldslim pointed out, the second (downstream) O2 sensor is used by the ECU to determine if the catalytic converter is working at full efficiency. If the ECU judges the efficiency to have fallen below an acceptable threshold, the P0420 code is the result. The obvious root cause is the converter itself, but a failed downstream O2 sensor can also …104 posts · Joined 2008. #2 · Oct 3, 2011. I as well have been dealing with the P0420 and a local subie dealer out here mentioned basically to clear the code and see how long it takes for it to come back up. Meanwhile, run fuel cleaner through the system to clear up the injectors and the 02 sensors. You said your putting the anti-foulers on ...P0420 data interpretation, 2007 2.5 non-turbo. Hi all! Ive collecred some data and am hoping someone can help me figure out my next step. I have a 2007 outback. 2.5i. 200,000km. A few weeks ago, the coil burnt out and I lost cylinder 3&4. I drove about 5km home hoping to avoid a late night tow bill.633. 176K views 8 years ago. This low kilometer Subaru Impreza flags a P0420 Catalyst efficiency fault code very quickly. The rear O2 sensor would behave almost like the catalytic converter had...B. bdubbs84 Discussion starter. 13 posts · Joined 2008. #7 · Oct 20, 2008 (Edited) Well, I got rid of the P0420 catalyst code, but now I have two new codes. One is P0440 (Evap. Emission Control System Malfunction) and the other is P0136 (O2 Sensor Circuit Malfunction, Bank 1 Sensor 2). I already have the O2 sensor spacer in place.How to diagnose code P0420 on a Subaru Legacy. Typically, you'll find out about P0420 because your malfunction indicator lamp or "check engine light" turned on & you or a mechanic diagnosed the problem with an OBD II code scanner like this one from Bluedriver. You may experience a very slight reduction in engine power from reduced exhaust flow ...The P0420 set the CEL AND made the cruise contrl light blink. The Cel is obvious as to why it was on. The P0420 did that. Now the blinking cruise, On Subaru's with 'drive-by-wire' the cruise control is integrated into the ECU, but is a seperate co-processor. If it detects any engine faults that will cause it to malfuction, it will disable ...P0420 Hard to start Help! 2002 Forester L. 136k Manual transmission. Bought this car about a month ago (first subaru) about a week into owning the car it developed a small intermittent start issue. Basically when the engine is WARM it will crank 2-3 times then misfire. Turning the key off then back on it almost always cranks once and …The P0420 code in a Subaru Outback is typically triggered by issues related to the vehicle’s catalytic converter. One common cause is a faulty or damaged catalytic converter, which may be clogged or no longer functioning properly. Another possible cause is an oxygen sensor failure, specifically the downstream oxygen sensor, which measures …P0420 code is the rear sensor reading the O2 levels coming out of the cat are higher than what should be. (possible failing Cat) good sensor. P0136 is the computer reading a problem with the sensor. Just did a PO136 on a ladies 2001 Forester. Changed rear sensor for $124 for part from Subaru and 20 minutes labor. ….

Tel: 01293 429800. Subaru UK's range of all-wheel drive SUV and family cars including the brand new Solterra and XV models. Discover the Subaru that fits into your world.Every mechanic has seen intermittent P0420's that come back after months or a year, that's common. A P0420 due to an oil filter is unheard of. More than likely the P0420 was intermittent and was going to go out and come back at some point no matter what you did. H6 OBW VDC, H6 OB Sedan, Tribeca, Lifted XT6. traildogck.According to Popular Mechanics Magazine, diagnosing the cause of a P0420 code on a Subaru Forester can be done by checking for potential issues with the catalytic converter, oxygen sensors, and exhaust system.This week Dana is working on correcting the issue of Code P0420, a Bad Catalytic Converter. We started this project off with a Dorman aftermarket catalytic c...This low kilometer Subaru Impreza flags a P0420 Catalyst efficiency fault code very quickly. The rear O2 sensor would behave almost like the catalytic converter had been removed. Replacement ...How to diagnose code P0420 on a Subaru Impreza. Typically, you'll find out about P0420 because your malfunction indicator lamp or "check engine light" turned on & you or a mechanic diagnosed the problem with an OBD II code scanner like this one from Bluedriver. You may experience a very slight reduction in engine power from reduced exhaust flow ...The most common fix for P0420 in the Subaru Tribeca is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Tribeca into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru Tribeca: 1.Dec 4, 2023 · 2010 outback2.5 code p0420. Hi all! Last night after hitting a rough patch of road on the highway most of my dash lights lit up. Cruise and E brake light blinking, check engine and traction came on too. I took it to autozone just to get the code and p0420 Bank 1 came up in the test results. The Insider Trading Activity of Walbrecht John on Markets Insider. Indices Commodities Currencies StocksP0420 Subaru: Code Meaning, Causes, Symptoms, & Tech Notes. The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 … Subaru p0420, Subaru Mechanic: Mike Alberghini. Hello! P0420 is referring t the exhaust system. it could be something like an exhaust leak, bad oxygen sensor, or bad catalytic converter. The other 2 codes are not real codes, and are due to your scan tool not knowing how to read the codes given to it by the computer., P0420, catalytic converter, and rattle noise. Just purchased a 2002 Outback 2.5L, 4 cylinder, 4 Door sedan with 140,000 miles. After a couple of weeks the check engine light came on and the P0420 code was the diagnosis. After reading other post it appears I should replace the 02 sensors and see if that fixes the problem., 2013 Outback P0420 code. Hello, I am new to this forum and Subarus meaning that this is my first Subaru and first post. Thanks for all the great information. I currently have a P0420 code and am trying to determine the issue. I have a 2013 Outback with 121k miles which I bought back in March 2017. There were lean codes which were …, My P0420 code started this past February and it has been driving me crazy. I started with replacing the pcv, code still there, then I used the Seafoam method. That cleared the code for a few weeks just enough to help me pass my inspection in August., Subaru WRX P0420 OBDII Code Defined. P0420 is generic (has the same meaning for all vehicles made in 1996+) OBDII trouble code. Here’s the technical …, The "official" fixes for a P0420 code are: replace the rear O2 sensor, replace the front O2 sensor and replace the cats. - Replacing the rear O2 sensor will accomplish nothing, IMHO - Replacing the front sensor is a good idea, since it is responsible for running the engine properly. Sadly, it probably won't solve the P0420 code issue., My P0420 code started this past February and it has been driving me crazy. I started with replacing the pcv, code still there, then I used the Seafoam method. That cleared the code for a few weeks just enough to help me pass my inspection in August., Find out what the best sign font options are for your small business for creating a visually attractive sign your customers find appealing. If you buy something through our links, ..., Code P0420 Description. The Engine Control Module (ECM) uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency. The first sensor, the air-fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to …, 4 posts · Joined 2015. #1 · Nov 16, 2015. my 2004 Subaru outback with 140k miles and Cali emissions has been throwing the dreaded P0420 code for almost 2 years now. I snuck it past inspection with a well timed code reset. However I want my cruise control back. I've read a number of the write ups on the P0420 code., Ran my OBD2 scanner and turns out I have a catalytic converter code failing code (P0420). I remember this happening to me about 4-5 years ago but all I did was clear the code and i’m pretty sure it never came back until very recently. ... /r/WRX is a place for Subaru fanatics to show off their rides, discuss modifications, mechanical issues ..., The most common fix for P0420 in the Subaru Tribeca is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Tribeca into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru Tribeca: 1., My '11 (140k miles) has been throwing a P0420 code along with running a bit rough, it stalls from a start (oddly the autostart has no issues keeping it running), and I'd say I'm down to about 70% power overall. The dash is lit up like a Christmas tree with the cruise flashing and two vehicle dynamics lights on., GM CEO Mary Barra sees the automaker selling personal autonomous vehicles by the end of the decade by leveraging technology from its self-driving subsidiary Cruise, according to co..., I've read on the forum that the p0420 code is a cat replacement. I brought this up to them earlier today and they wanted to do the spark plug replacement. I plan to call them tomorrow but wanted to get your all's thoughts/advice. Should I contact Subaru of America tomorrow as well?, B. bluewagon Discussion starter. 83 posts · Joined 2015. #1 · Mar 4, 2016. Hey guys, Like to get your thoughts on this. CEL went off with a P0420 code. FreeSSM description is "Catalyst System Efficiency Below Threshold:". From what I've gathered this kind of CEL could be fault of either the front o2, back o2 sensor or the catalytic converter., The P0420 is a finicky code. There is a range of "acceptable" parameters that Subaru has set. If the O2 sensor sees a value that is outside of that range, even for just a fraction of a second, you get the P0420. Adding the extension doesn't stop the O2 sensor from working, it just doesn't get the immediate read, but more of a mixed read., This week Dana is working on correcting the issue of Code P0420, a Bad Catalytic Converter. We started this project off with a Dorman aftermarket catalytic c..., The most common fix for P0420 in the Subaru Tribeca is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Tribeca into an exhaust shop for an (expensive) new catalytic converter, let’s ensure that’s what you need. Here’s a good P0420 diagnostic order for the Subaru Tribeca: 1., Obesity affects our health and earnings. On average, obesity costs an extra $3,439 annually. Here's how to lose weight without losing money. By clicking "TRY IT", I agree to receiv..., Check Engine Light P0420. My check engine light has been going on and off for 2 years. I have owned the car for 2.5. My local mechanic wants to install new catalytic converters. I took it to another shop for a 2nd opinion, 6 months ago. They suggested upstream O2 sensor (one of the 2) was bad and I let them replace it., Every mechanic has seen intermittent P0420's that come back after months or a year, that's common. A P0420 due to an oil filter is unheard of. More than likely the P0420 was intermittent and was going to go out and come back at some point no matter what you did. H6 OBW VDC, H6 OB Sedan, Tribeca, Lifted XT6. traildogck., Jul 18, 2017 · Also, P0420 can be the cat, but it can be a number of other things including rear O2 sensor, intake/exhaust leak messing with the air fuel ratio, spark plugs, fuel ... , There are several potential causes for Subaru code P0420, including a faulty catalytic converter, oxygen sensor malfunction, exhaust leaks, engine misfires, or issues with the fuel system. It is important to diagnose the specific cause accurately to determine the appropriate course of action., Protects the catalytic converter from clogging with soot. Cleans the injection system and the combustion chamber. The combustion improver works directly, which leads to an immediate, measurable reduction of the pollutants. Clean engines use …, In 2021, I had a lot of fun working to track down a P0420 code. As a result of this, I found several other issues with my 2016 WRX (manual transmission), and fixed them. The following have been successfully done: Full engine rebuild (new pistons, bearings, gaskets.... the works) - No mechanical issues. No fluid leaks of any kind., The "official" fixes for a P0420 code are: replace the rear O2 sensor, replace the front O2 sensor and replace the cats. - Replacing the rear O2 sensor will accomplish nothing, IMHO - Replacing the front sensor is a good idea, since it is responsible for running the engine properly. Sadly, it probably won't solve the P0420 code issue., p0420 catalyst efficiency low bank 1. I have had my check engine light come on and go off several times in the past 9 months, but the last time it came on it did not go off, so I took it to aplace to find out what is the problem, so he hooks it uo to this snap on computer and read the code as p0420 catalyst efficiency bank 1, and he rests it., Bluedriver diagnostic tool: https://amzn.to/2Vk2XjjO2 sensor socket: https://amzn.to/2TexLPPFixing the P0420 code is easy. First, make sure you're all cau..., In this video, we're going to show you a quick and easy way to fix your P0420 without having to replace your catalytic converter. This is a quick and easy fi..., Obesity affects our health and earnings. On average, obesity costs an extra $3,439 annually. Here's how to lose weight without losing money. By clicking "TRY IT", I agree to receiv..., May 23, 2011 · P0420 is VERY RARELY a failing cat. It is most commonly a failing oxygen sensor (front Subaru, rear any brand), vacuum leak, exhaust leak or what not. Search that code on the forums and you'll find plenty of info. Cats rarely fail without serious mechanical problems, I think your mechanic wants to give you an expensive repair bill. , There's some good information from that post onward. The gist of these messages and threads is this: to deal with a P0420 code on 2005+ vehicles, the ECU should be remapped to exclude this code, rather then using the $5 fix. The reasoning is that the rear O2 sensor is actually used to manage the engine, at least a little bit, rather than just ...