Hi and thank you for this video. This was extemely useful and thoughtfully done. I followed all of your recommendations. I just wanted to share, for all who come here in the future, that I was lucky and escaped having to replace the CAT. We've got a 2010 Forester with the dreaded P0420 error. The car runs fine and we get no other codes. I spent some time researching and scanning with my code reader and everything else was fine. The CAT temp was getting up to 1600F so I thought it weird that it was inefficient, but I don't really know. I tried graphing the O2 sensors but could not make much of that either. My rear O2 sensor graph looked a lot like yours with occassional dips. Watching other videos, I realized that only a genuine Subaru CAT was going to work. A local dealer offered me one at cost: $3200 US. Online, genuine parts prices are around $2K. Though there were no codes for the O2 sensors, I decided to replace them both before outlaying for a CAT. I planned to keep the car and was going to replace them anyway if i bought a CAT. Well, no need- the CEL went off right away. Boy was I elated! I used Denso OEM sensors: Front- 2349123, Rear- 2344445. As you stated, check for and fix ANY exhaust leaks, you must address them first. BTW: Subaru has extended their warranty on CATs to 150,000 miles for many models, so check with a dealer if your car is below that. Ours has 159K so no freebee! While I was at it, I gave it a tuneup: new iridium spark plugs, PCV valve (critical on oil burners like Subaru), oil change, air filter. Thank you for this great channel!

To find a leak on your exhaust system: Induce a source or air thru your tail pipe (shops vac output, hair dryer, leaf blower, etc.) and spray generously the entire pipe with a loaded mixture of dish soap and water.

@chelle315

2 жыл бұрын

A hair dryer is a great idea!! Thanks for that one!! 👍🏾

@Sumermak

2 жыл бұрын

Hey, just curious… I’ve had my pipe welded multiple times in different areas and I’m still getting that code, should I just replace the cat?

@danmc2678

Жыл бұрын

@@Sumermak Replace it. Get a reputable brand with a long warranty or OEM.

@Sumermak

Жыл бұрын

@@danmc2678 I did. The codes have dropped. Car this much better now.

@naughtyotter5547

Жыл бұрын

@@Sumermak did you go aftermarket or oem?

the only video I've seen that using bing as search engine

My 2017 Forester has a bad exhaust or oil smell coming from the engine compartment and exhaust. There is no sign of oil or any other leaks. Online forums have suggested replacing the PCV valve. The Subaru shop says it needs a new CAT even though the only symptom is the smell. There's no code. No loss of power. They tried to suggest that it sounds loud when it's cold but gets quieter when it warms up... 'Not really' I said. I'm not jumping into the line of fire of a $3500 parts cannon. I'm going to pull the PCV valve and see if it rattles and replace it either way. $20.00.

my car got this problem. one mechanic told me to use fuel injector cleaner everytime i refuel from empty tank. day 8 is running and check engine light did not come up yet.

Team - Great video. At time 8:20 you state the dip in the voltage data stream could be a bad sensor or cat converter. However, in the conclusion you state it is the cat. How can you determine if it is the rear O2 sensor (easy replacement ~$100) or the cat needs to be replaced (>$500 and hard labor)?

My 2009 Forester with 174k on it is now throwing cat codes. I wonder if changing both sensors out first before replacing cat?

Hey great video just got a p0420 on my 08 suabru impreza. I determined that yes my cat is bad but my question is can you tell me what caused it to go bad. Cause I dont want to change the cat for it to go bad in a year or two. Is this a common problem for my impreza?

An aftermarket Exaust manifold will eventually throw a code on a Subaru. I had the exaust replaced on our 2015 Subaru Outback due to a cracked exhaust. The Walker brand replacement is already throwing a code. Apparently, aftermarket Catalytic converters are not manufactured to the same specifications as OEM and will cause issues in a short amount of time. Mine made 10 months. Now I have to order OEM and replace that Walker. The garage that did the first repair went out of business. So I am screwed.

Hi, my check engine light on today . It say catalytic converter defect . But I have change it one month ago . Anyway I erase the code and check engine light gone . So my question is will it come back again. If so how long it will take to come back. Thanks Golf 5 ( 2008 ) 1.4 patrol engine

yah i have that code too. I checked today. Need o2 sesnsor? I have 110k on it. Thanks

@CarsNToys Car is a 2004 Subaru Impreza WRX at idle rear o2 sensor is stable at the low value like 0.045v. I see yours is hugging the upper value rather then the lower value. Is this strange to you?? I'm troubleshooting a p0420 code

How does an exhaust leak sounds?

That weld you see is likely from the expansion joints cracking. Happened to my 2010 Forester within 5 years of owning it. Joints are cheap and easily welded in. Subaru uses crap metal for everything. I've never had a vehicle with so much rust underneath on the exhaust system. I even have rust above my rear license plate fro crappy screws that are under the plastic moulding above it.

@anothersomebody8195

3 жыл бұрын

They also use plastic for everything. I would never buy a subaru new after getting a used 2002.

@mmark8394

3 жыл бұрын

Have 2002 subie, no rust, 390,000km runs well 02 post cat is a dud, no heater continuity, +0.8 volts output thinking to put a resistor across the heater to con the obd, do you think this will work? Mark in Australia

My Acura TL started throwing this code around 180k miles. Used to come on every two weeks. Most recently, I reset the check engine light and religiously go to the same Shell gas station every time (and buy recommended premium). Now at 205k and the light hasn’t been back on in months.

@futureshock7425

4 жыл бұрын

im gonna try just running on premium before I go to emissions, think it'll work?

@wilsongallagher-smith8333

4 жыл бұрын

future shock worth a shot. Eliminating the knock sensor going off from using anything lower than 93 octane might work

@ketanarora9619

2 жыл бұрын

Was it running rough while the code P0420 ?

I have never seen a bad o2 cause a 420, if anything a p0420 would tell you the o2 is working

Have you tried sea foam on you're cats by removing the front 02 sensor what do you know about tid 1 Cid 1

I was told subaru has extended the warranty on cat. conv. 15 yr. 150k . I know this one in vid is 170+k but all you in the miles and years check it out.

thank you saves me money

thank you very nice.

@CarsNToys

4 жыл бұрын

Welcome 😊

Where you buy yuo scanner?

Great video as always. Looking forward to watching the follow-up with the replacement!

@beaujude9412

2 жыл бұрын

I know im asking the wrong place but does any of you know of a method to log back into an instagram account?? I somehow lost the login password. I appreciate any help you can offer me!

@lucajensen5559

2 жыл бұрын

@Beau Jude instablaster ;)

@beaujude9412

2 жыл бұрын

@Luca Jensen I really appreciate your reply. I got to the site through google and Im trying it out now. Seems to take quite some time so I will get back to you later with my results.

@beaujude9412

2 жыл бұрын

@Luca Jensen it did the trick and I actually got access to my account again. I'm so happy! Thanks so much, you saved my ass!

@lucajensen5559

2 жыл бұрын

@Beau Jude Happy to help =)

I always thought the P0420 engine code meant time to toke another one

@shagytrsc2

2 жыл бұрын

You can do that after you Diagnose your code, and share it with whoever helped you.

@danmc2678

Жыл бұрын

kzread.info/dash/bejne/ooebqaWIeNi1Ybg.html

I honestly don’t feel comfortable going underneath a vehicle anymore just had a car fall on top of my friend for using the jack that comes with his car. I got jack stands at home and a good jack but might have to take it to shop .

@nicolasclermont893

4 ай бұрын

It's always good to be cautious but yes those jacks that come with the car can be dangerous if not placed properly or placed on an unlevel ground. Always always use jack stands when using a jack. Also leave the jack in place even when using jack stands.

How can you tell which catalytic converters should be changed? If you change one should you change the other?

@scottfirman

8 ай бұрын

On a Subaru, you replace the entire exhaust manifold.

Just put a 3 inch catless downpipe on my st and this code got through up it won’t harm it will it?

@j.b.9895

3 жыл бұрын

If you’re in a state that has periodic emissions testing, you will fail

Guys clean the cat and o2 with brake clean and soap. It seriously works

@generaldoomer2455

3 жыл бұрын

So I don't need to buy a new one sometimes like people say? I was actually about to kms if I needed to buy a new one

@scottfirman

8 ай бұрын

Not on a Subaru, get real.

so question? what does not changing cat do, when its the problem? my family all drive subarus. my brother been through p0420 for over a year now and drives it daily and move cross the country pulled a uhaul. still hasn't fixed the code I know its not leak or 02 sensor because I got him to change thouse. my sister just bought a subaru that code came on a day after she bought it she came in I checked code was def ,p0420. I don't know whether to tell her to hurry and fix it or what will happen if she doesn't take care of it. thanks

@CarsNToys

3 жыл бұрын

Long story short, the vehicle won't pass for emissions.

@srinivasdandibhotla5544

Жыл бұрын

can affect mpg (fuel economy) too

@scottfirman

8 ай бұрын

It's usually the Cats, period. Avoid aftermarket at ALL COSTS, they fail because they are not manufactured to OEM specs.

My 02 camry.......trouble codes: po0420,po0300,po0301,and po0302........causes? Check engine light was on.....pulled the codes......engine light went out.....45 mile drive.....no engine light Rechecked for trouble codes.....found the 4 codes listed.....now what...light bulb burned out???

@IamChordyceps

2 жыл бұрын

Alternator

I got a 2011 Chevrolet Traverse i just bought with 222k miles. Test drove it 3 times before i bought it and ran fine every time. Had a 40 min drive home from lot and about 30 min in the rpms started to drop. I took it to auto zone and got it tested for free and they said it was a bad catalyst system low efficiency bank 1. Told me to try Cadi clean but they was out every where so i got a diff brand and it took the check engine light off but it still ran like shit. Put it in a shop and they charged me almost a k to replace the first one. I get it back and drive my wife to work that night and it does the same stuff. Took it back to auto zone and it pops for the same thing. Do you think it a bad o2 sensor or converter that is post to be new. Cant get no one to answer my call at the shop in 4 days. Also if it is o2 sensor are they required to fix it for free since they misdiagnosed my car. They even told me it was the converter.

@BeastyPLAYZ16

Жыл бұрын

If it ran fine before the code popped up then it's probably not your catalytic converter if it was your catalytic converter you would have known when you test drove it because it would have been sluggish if it was clogged because air can't go threw the exhaust

did you have any issues with this aftermarket cat afterwards?

@scottfirman

8 ай бұрын

He will. They are NOT manufactured to the same specifications as OEM and WILL fail.😊

question: there were two catalytic converters, how did you know which one needs replacing?

@edgarsanabia6874

3 жыл бұрын

When you read the code it will say bank 1 or bank 2

@MacB369

2 жыл бұрын

@@edgarsanabia6874 lmao bank 1 and bank 2 refer to which side of the engine….that would in NO WAY indicate front or rear catalytic converter lmao 🤣

@edgarsanabia6874

2 жыл бұрын

@@MacB369 if you have a v6 or v8 you have bank one and bank two cats and they can have down stream cats and guess what if your down stream cat is out chances is your cat in front is also gone 🤡

@shagytrsc2

2 жыл бұрын

P0420 is for your bank 1 ( where your Cyl # 1 is) p0430 is for your bank 2 ( The other bank)

@_RiseAgainst

2 жыл бұрын

Late to the party but in this case (4cyl) the one before the downstream O2 sensor. The car does not have a way of testing second cat towards the back of the vehicle

How are you sure it’s not the o2 sensor without trying to replace it first? Way cheaper I feel.

@edgarsanabia6874

3 жыл бұрын

You can monitor you rear 02 sensor while the vehicle is running and introduce a lean condition so create a vacuum leak take a hose off the manifold somewhere while still monitoring that rear sensor and watch it. say at idle it's reading .8v and then You introduce the lean condition and should drop down to .1v you can also create a rich condition and you can see it go back up on voltage that way you know your sensor is responding accurately

@UlluMickey

Жыл бұрын

I must agree with your O2 sensor question. the video ends as he says it has a bad bank 1 sensor 2 which is the rear sensor. there is no mention of just changing the rear sensor or if that is even an option. kind of left the video as a cliffhanger in my opinion.

@scottfirman

8 ай бұрын

Generally no, it's always the Catalytic converter on a Subaru. It could be a cracked exaust manifold too. Ours failed at 10700

First like from NYC

So, the sensor or the cat?

@_driver_

4 жыл бұрын

future shock did you finish the video?

@JonnyAbs-0

3 жыл бұрын

I think a bad sensor would not give a readout at all. It would likely be a flat line

Have that code and I don’t have a cat !!!!! That’s drive me crazy P0420 With No cat , units deleted

@leslie-tolman

3 жыл бұрын

Word of advice, from my own personal experience (currently ongoing shit situation that's getting real expensive, real quick)~ My first cat/exhaust manifold was throwing a code because it was clogged. I grew up with gear heads, hot rods and old-school muscle cars, always straight-piped, huge headers and even bigger blowers sticking out their hoods... I started working on cars only a year ago and thought gutting mine was a good idea. It was, until it wasn't..... it triggered my Gen 1 Scion tC's ECM fuel trims, increasing how much fuel is added to the combustion chamber by 25%. Increased performance was awesome.... until the fuel started flooding the pistons and getting past the rings, down into the oil... now I have to rebuild the engine because fuel dilutes the oil... all of my valve seals, crank seal, rear main seal, valve cover gasket and basically everything that's rubber or gasket sealant/maker is compromised and leaking. My piston rings aren't any good anyway and the main and rod bearings are likely damaged, likely scoring the crankshaft and camshafts along the way. By the time you realize you have fuel mixed in your oil, it's already too late!! Research how to diy or purchase an adapter for your 2nd O2 sensor... it doesn't always work for all vehicles but it can save you literally thousands of dollars and they're cheap AF. I didn't know then what I have learned the very expensive and painful way now. Don't just ignore it and no, replacing the sensor itself won't do shit to fix the problem!! Hope that helps you and others. Best of luck

Does Po420 code effects fuel economy

@darinstocks1184

3 жыл бұрын

NOPE.

@JonnyAbs-0

3 жыл бұрын

only if the cat is clogged

@NOName-nn3jv

3 жыл бұрын

Jonn Abshire and can I unclog a cat??

@JonnyAbs-0

3 жыл бұрын

@@NOName-nn3jv if the sibstrate is melted, no. If the catalyzing agents are just worn or covered in soot, you can try cataclean or running paint thinner. Google that. Do you have performance issues?

@JonnyAbs-0

3 жыл бұрын

@@NOName-nn3jv you could also try a spark plug defouler on the o2 sensor if the cat just won't pass

🙏🏼

Well after 1000$ for 3 O2 sensors on my 2000 camry V6 the light still on and won't pass inspection. The mechanic tells me I need to replace all 3 cat converters at 1500$ with labor. Selling the car as is. Stay away from Toyota....