Subaru Outback P0420 Again! Big Lesson Learned | Quick Diag and How to Replace the Converter

This Subaru Outback has a P0420 Again! I learned a big lesson about aftermarket converters.
🛒PARTS LIST:
▪️ Catalytic converter: Contact your local dealer
🛒TOOLS NEEDED:
▪️ Scan tool: amzn.to/3OlUCWO
▪️ 1/2 Impact: amzn.to/3Sfmiht
▪️ Impact socket set: amzn.to/3Hy3fKi
▪️ Torque wrench: amzn.to/3AgaOB2
▪️ Electric ratchet: amzn.to/3Sw4W12
▪️ Prybar set: amzn.to/3IkSlWw
😎If this video has been helpful consider supporting us with a cup of coffee! 🙂
www.buymeacoffee.com/ValleyMo...
➡️I am part of the Amazon affiliate program and get a small commission when purchases are made through the links provided.
🔺DISCLAIMER
The information provided by Valley Mobile Automotive (“we,” “us” or “our”) on this video is for general informational purposes and entertainment only and does not replace professional advice.
All information is provided in good faith; however, we make no representation or warranty of any kind, express or implied, regarding the accuracy, adequacy, validity, reliability, availability or completeness of any information on the video.
By working on your own vehicle, you take responsibility for the outcome.
Under no circumstance shall we have any liability to you for any loss or damage of any kind incurred as a result of the use or reliance on any information provided on this channel. Your reliance on any information on the videos on this channel is solely at your own risk.

[@mr.nobody4900]

Sometimes aftermarket products don't cut it... $1,700 for a freaking Catalytic Converter that's a crying shame...Well done

[@ValleyMobileAutomotive]

Yeah their 3 times what an aftermarket converter would be! But doing this for work I'm going to recommend OEM on these from now on. I don't want to be doing warranty work shortly down the road. This one was frustrating 😕

[@dq96708]

im trying strategize for our 2009 outback with this problem. our shop explained they have had the same experience you did and they only use the subaru parts also... I really want a used cat, but i’m told it is illegal to sell them.

[@chenupy77]

Amazing and wonderful details ,Thanks for taking your time and sharing to the broader Subaru owners

[@bgable7707]

EXCELLENT, I've been researching the P0420 for two days now. Your explanation and demonstration of the Temp, Pre and Post sensor readings really helped to bring all this together. Plus the added feed back from the muffler shop is good, but, not sure if I'm ready to spend $$$ on an OEM, darn.

[@beerwrenchgarage]

Very good video! Way to have confidence in your diagnosis to not only call a bad part on the replacement but also to convince the customer to spend $$$ on an OEM converter.

[@LChow-xq3xm]

Your video gave me more knowledge on this subject, thanks.

[@camiloguzmang]

Great input! Thanks for the advice you gave us!

[@missygetty73081]

i really like the way this was presented 💕❤

[@ValleyMobileAutomotive]

Hey thanks Jenna 👍

[@TmanT321]

Best video on this topic I've seen.

[@ValleyMobileAutomotive]

Thanks Mr. Cucumber 👍. It's crazy how expensive the dealer converters are. Good thing this vehicle only has one!

[@bbrandonachmalz4228]

interesting information. thank you

[@ZoeyZee]

Super informative thank you.

[@scottmagoch5367]

New subscriber,great video,thank you!!

[@kylekarsten721]

I just had my 2011 at the dealership for cats... quote came back at $9,110.50. I almost lit the car on fire. Went with Walker, so far the readings have been good. Fingers 🤞

[@ValleyMobileAutomotive]

Yeah it's ridiculous how expensive these cats are! When I went to the parts store for the warranty exchange they said walker discontinued the part number I had bought before. they have a new number so hopefully it's an updated part and and they fixed whatever was the issue before.

[@enrique4737]

I'm about to order a walker. How is yours holding up so far?

[@kylekarsten721]

@@enrique4737 so far so good. Put about 40k on it since the new cats went on

[@enrique4737]

@@kylekarsten721 that's awesome I just did mine and the walker one didn't have the threaded holes and I struggle to find some but I finally just went with M10s x 1.25 wish they were longer but they work.

[@Remnant144000]

​@@enrique4737aqaq

[@wafel19781]

Thank you very helpful

[@1984farnon]

Excellent tutorial:}

[@cantbuyrespect]

I was able to clean mine using citric acid. It even took the rust off the pipe. 15k miles and 1.5 years later no p0420 code.

[@chmv2252]

great job, thanks

[@srt8charger922]

Our 2008 outback, factory converter is 3800, Orange county California. Just the front converter. Thank God I've done all the work myself. video! Thanks for taking your time to post the video. God bless you in health and wealth. Subscribed to the channel. God bless you all working on these expensive subaru's. First and last subaru we'll own. I also want to burn this puppy down. Lol!

[@ValleyMobileAutomotive]

Glad this was helpful 👍. Welcome to the channel.

[@assininecomment1630]

Very good description, demonstration and explanation. Now I'm just concerned about how expensive tomorrow's exhaust workshop bill could be... (identical car, in Straya) 😬

[@onewickedgun1708]

Part f the issue with some of the aftermarket converter/manifolds, is the FLOW, if you will, they restrict flow to and or from the converter, causing the sensors to read and throw codes.

[@haqitman]

Thank you for this informative video! But jeez, as if the oil burning and head gasket issues aren't bad enough, throw super expensive converters into the equation. On our 07 Forester, we'll just keep resetting the check engine light until we get a new (non Subaru) car.

[@fredjackson8408]

Im about to just straight pipe mine if the replacement i ordered failed 😂 i didnt buy the OE spec converter but at this point any new converter is better than the box of rocks i got bolted on now

[@jaapattv7760]

this is actually good. you got a new sub!

[@ValleyMobileAutomotive]

Hey thanks!

[@jaapattv7760]

@@ValleyMobileAutomotive :)

[@borkganza9627]

New Sub here. Excellent video👍

[@ValleyMobileAutomotive]

Thanks Bork welcome to the channel 👍

[@griffenseye3732]

Yea you thanks for explain why parts cost more for quality. I noticed the larger chambers before and after the cat. Cool to see… it would be nice if we had a service for them. Like how to clean them that’s worth the effort. I herd lacquer thinner 1gal:1/2tank and 150 drive Miles. Any ideas?

[@leetos.4915]

When it comes to spark plugs, does it matter too if you get it from your brand (my case) Hyundai OEM compared to auto zone spark plugs? I totally agree with aftermarket cause and effect ....thanks much

[@ajgil8260]

Thank you. Excellent presentation. I have a 2017 Subaru Crosstrek. OEM cat replaced by Subaru dealer at 42,000. Now at 67,000 the P0420 has shown up again today. Replacing both sensors first to see if that's it. If this 2nd OEM cat is bad, I'm replacing it with a Toyota. The key to all this started at 11:50 - "One thing to keep in mind....." this summed up the whole Subaru cat issue in a nutshell.

[@MICKIN310]

My 2017 is throwing 520 codes yrs super expensive dealer only part how long it take to change any special tools ?

[@ajgil8260]

@MICKIN310 Turns out a clogged fuel injector caused my Code. Insane. Rough idle caused by fuel injector dripping rather than a mist, not a need for a new cat or sensor. I sold my Crosstrek and bought a RAV. I simply cannot waste time and money on crap like this...as much as I loved the Crosstrek I scrapped the rig.

[@donjames5761]

ive had nothing but problems out of WALKER everything from bad ' IAC's to o2 sensors cats

[@beerwrenchgarage]

So the cat was the P0420 code, but what was causing the rough running?

[@briceisright]

Thanks for the video. My walker cat cracked on the pipe before going into the collector. Had that welded and im still getting the 420 code. Im assuming the bad walker cat and oil consumption on the engine is causing these issues. Im trying the spark plug fowler to just get rid of the code for the time being to pass inspection until I can rip the engine out and buy an OEM cat. Subaru's new moto " You'll love it till you hate it!" Does anyone know if a MagnaFlow OEM cat is as good as a Subaru? Or will it be another walker issue? The MagnaFlow is cheaper than subaru but twice the cost of a walker.

[@erman445566]

I have the same experience with my 2009 2.5i 135K Subaru Legacy. I bought it used with 135K miles. I use an OBDII device that connects to my phone. Replaced both O2 sensors, cat (Walker/Rockauto), spark plugs, spark plug wires, air filter, cleaned the throttle body, cleaned the MAF sensor, corrected exhaust leaks, added an oil catch can, changed the timing belt and pulleys. The car runs well and now, there are no codes, except for P0420. After the cat was replaced, passed CA smog, it ran for about 3500 miles before P0420 returned. Since then, the code will return every 180 to 500 miles after clearing the code. I have also tried Cataclean (twice), and removing the cat and cleaning with detergent like so many other youtube videos. The federal exchange warranty is useless. In my case, I would have to purchase another cat, send back the faulty one ($$ shipping), and IF Walker determines that the cat was bad, they will reimburse. Why would I want to purchase another cat ($700) that is likely to fail in less than 4k miles just to have Walker say it was poisened by my high mileage engine? (I don't expect them to say it was a faulty cat, eventhough it looks like an OEM cat will work much better). So, now I am at 174K miles 16 months later. From your video, I am nearly convinced that if I want the P0420 code to go away, I will have to purchase a new OEM cat and install it before getting it smogged in 4 months when registration comes due. I really enjoy the way this car drives. Its even enjoyable to work on. I just wish it was illegal for aftermarket parts manufacturers to sell products that do not meet OEM specs and to seduce buyers with meaningless warrantees. "Big lesson learned" indeed...great video!

[@briceisright]

I did all the same for my 09 legacy. Im still battling the 420 code and pass my inspection. Although i do have bad oil consumption with the engine to boot. Im trying the apark plug fowler juat so I can pass inspection till I can get the OEM cat and rip out the engine ugh

[@dant3113]

So what did you do with the car?

[@KChourney]

Have you tried a o2 sensor spacer? That's tricks the computer and the cat. I hear good things. Trying it this weekend as I have the 420 with my Impreza. Lucky I live in Ontario where we don't do smog tests tho. I just want my cruise control back lol

[@asianstud7]

You said the aftermarket lasted 2 years. You know how many miles it lasted for that customer? Also, what was the brand of the second aftermarket converter you tried that did not work out for you before settling on the genuine Subaru one? Thanks.

[@jonathan3518]

Think I’m on this road. Wish your shop was closer. I’d just let you deal with it.

[@K03sport]

How often did the customer drive and what was the av drive time? Most cars suffer from under use and short trips. Not absolving Subaru from its issues but under use is just as bad as hard use

[@mattmontoya22]

You are in the 760 in vista? You're not far from me. Thank you for the fed regulation info and I think I'm going to ask that my mechanic go oem on the converter I need for my Impreza. For lambda because you were using your device as an oscilloscope you were talking about the distance peak to peak, correct??

[@forensic8385]

Subaru OEM "pretzel" converters are up to $2200 just for the part, incredible.

[@JohnStax98]

Very good video, do you think the aftermarket one would las ta few thousand miles at least? Or would it have caused a check engine light right away because of the efficiency.

[@ValleyMobileAutomotive]

The first one lasted 2 years. The second one was junk out of the box. That one would have set a code once the converter monitor was completed.

[@GabrielM01]

so there no reason to buy a aftermaket cat? so cat delete it is

[@juliosdiy3206]

So if the exaust cant get through the converters then where did it go?

[@asianstud7]

Can someone get all those readings with a computer like yours? On a smartphone with something plugged in under the dash?

[@hieptruong5222]

may cat was clogged also the up-pipe and they wanted 4k to change it

[@sunzoutgunzout8887]

There is a second cat under the heat shield that fails and plugs the exhaust

[@andinamm2246]

Hello Great video Have subaru crisstreck first gen. Have same readings on oxigen sensor BUT...i also hace water coming out of exaust...is that head gasket?...or converter? Thank you sonmuch

[@ValleyMobileAutomotive]

Some water in the exhaust is a normal byproduct of the catalyst process. You'll notice drips of water out of the tailpipe or a weep hole in your muffler.

[@tdang9528]

was it due to the DENSOs?

[@stephengodsoe5286]

I changed out my front cat with an ap eastern. Ran amazing for 35 seconds. Now running like crap again. Can’t accelerate and shaking back and forth. Midas says it’s the rear cat too. What do you think?

[@ValleyMobileAutomotive]

It could be the rear cat. A plugged exhaust will make a car run horrible and sometimes make them not run at all. What you can do is disconnect the exhaust behind the front cat and see if it runs better. If it does then reconnect the exhaust and unbolt it behind the rear cat and see if it acts up again.

[@SEBAS31077]

what was both cost

[@TmanT321]

Hey, just trying to diagnose a Cat issue right now on a 2009 outback. I ran some tests with my OBDII reader and the B1S1 reading sticks around 0.99 lambda under load (2000rpm) or at idle, but the reading i get for O2S B1S2 is around 0.865 to 0.9(V) under load and fluctuates a lot at idle. That second number seems high to me, but I don't have any fluctuations according to the graphs I'm seeing . The CEL only kicks on after I drive the thing for around 10-30 minutes at around 2500rpm, and shows P0420, and it doesn't do it every time it seems pretty random. Just trying to figure out what best course of action is and what is most likely cause in your opinion. Any input is appreciated. Was gonna run some cataclean through it tomorrow to see if that helped.

[@ValleyMobileAutomotive]

Under acceleration the engine will be richer than normal so the rear o2 will read a higher voltage. When you let off the throttle and are decelerating the fuel injectors should shut off causing the engine to be lean and the rear o2 voltage will be low. That's normal operation. The car should be checked at idle and a steady cruise on relatively flat ground. The rear o2 should be steady above 0.5 volts (typically 0.6-0.7). The 0.99 lambda is good. Before replacing a cat make sure you're not burning oil and or coolant. Eventually this will kill your new cat and you're stuck giving them your second child for a new converter.

[@TmanT321]

@@ValleyMobileAutomotive thank you, your input is much appreciated. I think I've narrowed it down.

[@bmc5180]

@@TmanT321 What ever came of this? I'm in the same boat with a 2012 Outback. My B1S2 sensor is all over the place when at idle, but is steady and >.8 when under load. I suspect a pinhole exhaust leak, but I haven't been able to find it. CEL is currently off, but has come on twice this year.

[@alaaalattar7495]

What diagnosis device are you using? How you get the results on your phone?

[@ValleyMobileAutomotive]

I'm using the Launch X431. There are a good number of options out there for using your phone. The only one I've had experience with is Blue Driver. You just need a tool that can read and graph live engine data with a good refresh rate.

[@consaka1]

That cat is now worth more than the car.

[@MICKIN310]

I’m having to replace mine any special tools needed ? How long it take you ?

[@ValleyMobileAutomotive]

You just need an oxygen sensor socket. Other than that regular hand tools should work (if not too rusty). It takes about 1-2 hours if everything comes off smoothly 👍

[@michaelmartin2276]

What about the rear converter ? How to diagnose which one has failed ?

[@ValleyMobileAutomotive]

The rear converter is not monitored by the engine computer. If you have a converter code it's for the front converter.

[@dant3113]

I have a 2013 crosstrek with 138k miles. Just got code p0420 can you replace the cst with a used one? I live in Cali so i cant just buy an aftermarket one.

[@ValleyMobileAutomotive]

The sale of used converters is illegal in most if not all states.

[@dant3113]

@@ValleyMobileAutomotive that's so stupid. So they want us to spend thousands on new ones

[@Mrlocdown238]

Some subies require a California cat or a EPA cat.

[@ValleyMobileAutomotive]

True. Depending on the state you live in. If you get the converter from the dealer it should automatically be the converter you need.

[@deoxribonucleicacid8746]

​@@ValleyMobileAutomotivewill the VIN denote California emissions vehicle? Bought mine used, turns out it's from Virginia, i think. Not sure where before that.

[@ValleyMobileAutomotive]

@@deoxribonucleicacid8746 I believe so. You can contact a Subaru dealer and ask the parts department if your VIN is California or Federal emissions 👍

[@stanislavtodorov8705]

Didn't get it, why you replaced the cat converter. you said "check oil level, check for exhaust leaks, check O2 sensors". You found exhaust leak but still decided to replace it anyway. What was the reason, besides it was still under warranty?

[@ValleyMobileAutomotive]

Good question. Apparently I didn't film it but new gaskets were installed and the converter was still not able to keep up with the demand.

[@stanislavtodorov8705]

@@ValleyMobileAutomotive thanks for the reply 🙂 that was unfortunate, given the prise of the converter. Anyway learned something about the behaviour of the O² sensors which will help me diagnose my p219E error code. Cheers.

[@lorrainenicoletti6232]

My mechanic was quoted $7,000 For a new subaru Catalytic converter for my 2005 Forester. Of course this doesn’t include service and Labor. Any info is really welcomed Is this really inflated or is it real ??? The car has 74,000. Miles on it and I wanted to keep it?

[@ValleyMobileAutomotive]

Prices have definitely gone up but that seems like a lot. I would suggest calling the dealer and asking them directly what the price of a converter would cost. Most shops will double the price of parts they get for resale. This helps cover any possible warranty claims associated with the repair. So a $7,000 dollar part may only actually cost $3,500. I'm not sure how the shop you took it to operates though. Some places will allow you to bring your own parts with the caveat that you won't get a warranty with it. But if it saves you $3,500 then it might be worth it. Just some thoughts.

[@cantbuyrespect]

You can clean it with a citric acid soluton. I did mine and for less then $200 for new o2 sensors and gaskets mine is fixed. I have drove 15k miles over 1.5 years and no p0420 code. Look up the process and save yourself some money.

[@BrandonSalas-us8mm]

Yeah just wrapped up a manivert on a sport trex what a pain in the ass solid pipe 600 dollars for a carb compliant piece of shit

[@577buttfan]

Im so sick of the EPA polution bullshit really am!! Its all a money scam.