P0420 CODE CAUSES AND SOLUTIONS

In this video, you'll learn the causes and solutions of the P0420 code. The causes of the P0420 code are a bad catalytic converter, an ECM update, an exhaust leak before the catalytic converter, a faulty oxygen sensor, and damaged or corroded connectors. The solution for the P0420 code is to repair whatever caused the code to occur in the first place. You will also learn how the P0420 code appears. In addition, you will learn what the P0420 code means.
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#P0420 #P0420Code
Search terms and questions you might be thinking related to the P0420 code are:
What are the causes of the P0420 code?
Causes of the P0420 code
Solutions for the P0420 code
What are the solutions for the P0420 code?
What does the P0420 code mean?
P0420 Code
What causes the P0420 code?
How to fix the P0420 code?
Where is the oxygen sensor located in the car?
Bad catalytic converter
Catalytic converter P0420 code
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[@easyautofix]

OBD2 Scanner: amzn.to/3PHRplS

[@jeffsond]

My sons scanner pulled a PO420. It wasn’t in limp mode, my mistake. After driving it I believed it to be a clogged cat. He had the 2 cats near the engine changed 1 1/2-2 years ago. We looked under the van and the 2 cats Y into a single 3rd cat that wasn’t changed. We believe it’s clogged and will be pulling it off to check tomorrow.

[@guywhite1004]

I have a 2013 Buick Encore with 155,000 miles on it. I had replaced the upstream O2 sensor when I got the P0420 code since it was the easiest to get to and was the cheapest. This did not help. Due to a faulty EGR valve that had to be replaced previously, my mechanic said that the excess oil being burned probably had fouled my catalytic converter, so I had that replaced. This did help the engine run better, but I still had the P0420 code. I checked my downstream O2 sensor with my scanner and it was fluctuating the same as the uopstream O2 snesor. I ordered one of the O2 Sensor adaptor from Walmart. This seemed to be a better alternative to the Spark Plug extenders that other You Tubers recommended since the Walmart extender was Stainless Steel rather than aluminum, and Stainless will hold up much better in the high temperature environment of the exhaust system. I received the O2 sensor adaptor from Walmart two days later, and installed it at the downstream O2 sensor location. I reset my P0420 error code. We have driven over 300 miles with the sensor extender in place and the engine check light has not come back on. The P0420 error code has not came back either. Best money I have ever spent on this problem. Thank you sir for your You Tube video. I have no doubt that my catalytic converter needed replacement, but I just could not eliminate the error code. Thanks again!

[@TurboMountTV]

Using the extender you just turned the code off, your didn't fix the underlying issue causing the code.

[@guywhite1004]

@@TurboMountTV

[@guywhite1004]

The downstream O2 sensor began working correctly and the catalytic converter was replaced with a new one. The sensor fluctuations confirm that it had fixeed the problem.

[@TurboMountTV]

@@guywhite1004 You may want to have tried a cat cleaner before replacing it?

[@guywhite1004]

I did before I had the converter replaced. The man that replaced the converter said it was still clogged up

[@howtodoitdude1662]

This is the best, clearest explanation of code 420, thanks! Subscribed.

[@easyautofix]

Thank you, very nice!

[@borntowin1017]

I love your videos very knowledgeable! Learn a lot from you sir! My name is TASHA from USA 🇺🇸. My check engine light reads that I need to replace ignition coil and spark plugs as well as a cylinder 4 misfire secondary DTCs, p0420 cat efficiency helper threshold bank 1 and 83-13 ECM/PCM relation failure. I have a Honda Accord 2009 LX. I’ve driven like this 7 years! Now I fear how much repair will cost. Why me? 😩

[@MrBigkilla]

Good stuff...thanks for the knowledge! You guys save us tons of time and money. I have a misfire in #7, replacd coil and plug.....drove for 30 miles, now have a P0420 and a P1283....uggh...back to youtube...

[@HarrisonHunt-mj4ez]

I had a Misfire with #1 and #4 but I drove home 10 miles , changed the coils and spark plugs and leads , no engine light but 15 miles in I get p0440 , I think the excess fuel has ruined my cat , I changed the upstream sensor and changing the downstream one next , did you end up fixing it ? I also have p0420 and 440

[@Arcticfox7]

Thanks, Chris

[@krakenhits1587]

Last time I was due for inspection I used cataclean and it turned off my but I'm not sure if it was only a pending code now I'm getting a permanent p420 code if I use it again and it doesn't turn it off do I have to reset the code myself because it's a permanent code and then see if it comes back

[@Vellieveil_64]

I have the same code P0420. Cat 2 years old. New 02 sensor. Code popped up when I replaced the purge valve..What could be the problem? Thx

[@nosajsamaniego4512]

CAN YOU DO, "Symptoms of a bad Radiator Inlet/Outlet Tank," NEXT, PLEASE???!!!

[@josiahflores2191]

I have a 2010 mitsubishi lancer and i replaced the cat and i replaced the oxygen sensor bank 1 sensor 2 and the code still popped up. I have two sensors left to replace it’s either upstream or that sensor before the cat. I’m tired of wasting money please help!

[@lionstrength1966]

I have a 09 ford f150. When driving and when I hit around 30mph there's a big CLUNK noise coming from under my truck like by driver seat. When diagnosed engine code was p0420

[@jeffsond]

My son’s van went into limp mode. 2006 Kia Sedona with 239,000 miles. He had the cats replaced about 1 1/2 years ago. I’m hoping it’s the o2 sensor. So you think it may be the one before the cats?

[@phuqizm1547]

Oxygen sensor is usually the issue.

[@Isaiaha400]

Ive been struggling with this code on my toyota corolla. Changed cat, both o2 sensors, muffler, and exhaust manifold.

[@thewiseguy7100]

Did you find the solution man? I have a Toyota Camry P0420 and P0172

[@Isaiaha400]

@TheWiseGuy no..let me know if you do!

[@thewiseguy7100]

@@Isaiaha400 Not yet, replaced the oxygen sensor and Map sensor. Going to clean the MAF sensor

[@Isaiaha400]

@TheWiseGuy i havnt done the map or maf sensors. Im going to try that. Thank you for the support 🙏🏽!

[@thewiseguy7100]

@@Isaiaha400 No problem, I’m hoping cleaning the MAF sensor today going to fix the problem

[@arc6100]

Can wrong spark plugs trigger p0420? I get a strong smell of unburnt fuel

[@StBeter-tc2te]

if they were wrong you’d hear a knock on the pistons because the thread is too long or the car wouldn’t start because there’s no snugged spark plug on the pistons.

[@skillsrobles]

i replaced the manifold, catalytic converter, and oxygen sensors and still get the p420 code on my cobalt. But its weird that when the emissions test passes the catalytic converter or is ready, it gives me that code. But my evap system is not ready but give me no codes for that. Ive also cleaned my throttle body and injectors. What can be causing my issues?

[@supeme3153]

Reset codes?

[@skyloveup]

Dang 😮

[@1000ramd]

Hello everyone. I'm curious if anyone has any suggestions about my p0420 code (low efficiency, bank 1). I bought a 2016 Encore, base model with 100k miles on it. I just changed the cat and both o2 censors but the light came back on about 60 miles after the change. Before it came back on I heard a odd humming sound and it felt like it was running a little rough while driving for a few seconds. After letting it cool down I turned the car back on and sprayed the immediate area before and after the cat with soapy water to see if there was a leak but didn't find anything. Any idea what it could be? Thanks.

[@Dontexxr]

How'd you check the leak? Did you plug your exhaust pipes? Honestly use a shop vac and then spray while it's running its much better

[@McAdamsMechanics]

Maf... egr valve.. o2 sensors... vacuum leak... cat block...

[@khielahbot]

Okay thanks

[@easyautofix]

And thank you!

[@Texas_Made_]

❤

[@brucemartin6307]

What do you think of Cataclean?

[@LOLONO666]

it does not work in 90%

[@cammgt3rs370]

He is right on. Cataclean is the sht. Used it on all my cars. It also makes the car more powerful, wink wink.

[@tomipoole2675]

I used that..and there is where everything went downhill.

[@scottykilmer3920]

what happened

[@christopher23.]

Can my air flow sensor create a p0420 code?I took mines out and it looked like a super tan color. Like shiny tan brown. Not sure if it’s supposed to be like that.

[@batuhaneraslan7186]

Could figure it out?

[@Lrv6532]

The engineers riigged the ecm pcm to force u too buy a expensive catalytic converter,like a monopoly moneymaker like sensors

[@gethomel]

Just purchased a wrx 2021 12/25/2021 took it in to subaru with 15000 miles. After i got it out the shop check engine light with blinking cruise control pops up on my dash. So i take it back in and they clear it. Light is gone and then it pops up again! I take it to autozone use their code reader and ibget P0420 catalyst efficiency below threshold. Maybe if i would have asked why the light poped on i would have got the problem fixed, but i assumed they would have told me. The car is pretty new and from what ive read about this code it could be a failed sensor hopefully. The car is under factory warranty still so hopefully its just that and i dont have a faulty cat.

[@wise_soul8886]

*any updates? What fixed it?*

[@gethomel]

@@wise_soul8886 Looking at the service report, cat and sensors were tested and are working fine but they found a cross thredded bolt. I dont remember exaclty where it was located but i know somewhere on my emission system. New bolt and retapped threads. They told me i needed a new catalytic converter. They ordered a new cat and the work was all under warranty. They didnt even need to use it because my catalytic converter turned out to be fine. I believe the issue was a vacuum leak caused by the cross threaded joint not sealing properly. Its been two weeks since ive had the car out the shop. No check engine light since then and the car is running fine. I wish i had my service receipt and i could type word for word what was done.

[@wise_soul8886]

@@gethomel *hmmm... yea thanks for the info, what bolt is the one you're talking about? both of my o2 sensors are good, car runs good, and everything sounds, and even smells good, no funny emission smell, and no wierd sounds coming from the catalytic converter. I cleaned out the intake yesterday with an air gun & air compressor and alot of black liquid came out of it. I'm not sure what it is. I don't believe it's oil because I've recently been checking the oil dipstick and it appears oil isn't going down! Before that i got another new code which is p0401. Still no fix tho :( ... this sucks*

[@gethomel]

@@wise_soul8886 They removed manifold assembly complete with turbo and seprate front catalytic converter. While removing catalytic converter from manifold assembly found crossthreaded stud. Had to remove and retap thread and installed new stud and nut.

[@colbyshelstad2004]

Extender

[@adnanramadanii]

My car sometimes stops the gas and while I'm checking the engine, I pressed the gas pedal too much, someone tells me

[@nosajsamaniego4512]

Explain;

[@user-ju8rr9rf1o]

Aftermarket cats will not stop the code either most of the time.

[@jasonstewart8973]

Man i give you a big hell yeh ive done this long long ago learned from an old man .when u tube started getten hot with all these smoking ideas.i say kill the light its all a mony racket an we know it .hell ant no way im gonna spend 300 or more to fox a cat when i can do that shit for under 20 bucks.keep rocking brother red neck way

[@kayrogers4024]

I don’t think you should recommend using the extender the light should stay on til the problem is fixed

[@LOLONO666]

this is prohibited too

[@Vellieveil_64]

Will the car pass the emissions test with the coupler attached?

[@acigaa1494]

I'm kind of surprised that none of the reason for the codes was that it got stolen XD.

[@victoraguilar3561]

He meant to said i have millions of them but basically having only one was his mistake meaning that a lot of people look up to him but has only one biological child

[@sim7409]

here in ohio we do away with cats