EricTheCarGuy Explains Check Engine Codes - P0420 Catalyst System Efficiency Below Threshold

Find your TRQ parts here: 1aau.to/m/ETCG0420
Eric the Car Guy is here! He's visiting TRQ to explain check engine codes to you! In this video, Eric the Car Guy checks out code P0420, which usually has to do with the catalytic converter. The full description of the code is “Catalyst System Efficiency Below Threshold (Bank 1)” and it generally means that the catalytic converter is not doing its job, usually because it’s clogged. For vehicles with a second bank, like most V configured engines, P0430 means the same thing, but on the other side. Check out the video to learn more!
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While TRQ strives to make the information provided in this video as accurate as possible, it makes no claims, promises, or guarantees about the accuracy, completeness or applicability of the content. No information contained in this video shall create any expressed or implied warranty or guarantee of any particular result. All do-it-yourself projects entail some risk. It is the sole responsibility of the viewer to assume this risk. TRQ is not responsible or liable for any loss damage (including, but not limited to, actual, consequential, or punitive), liability, claim, or any other injury or cause related to or resulting from any information posted in this video.

[@TRQ]

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[@Game-ib3ql]

Ive been driving with that p0420 code for 6 years

[@7-4-76]

Great move, TRQ, bringing Erick to the channel. He will bring a lot of viewers. ❤

[@rasmadrak]

I had a P0420 code on my recently purchased car, despite it having a brand new catalytic converter. I replaced the O2 sensors (since the cat was new) but the code remained. In the end I found that the spark plugs were bad and had killed the new converter by dumping unburnt fuel into it. After replacing the cat again, the code disappeared. So yeah, trust the OBD readings imho :)

[@03maxi]

I had a p0420 on my 09 versa, I replaced the converter with a cheap aftermarket one, it not only did not fix the issue, it made the exhaust fumes smell super awful which then protruded into the cabin. I had to bite the bullet and buy a genuine nissan oem part, however it fixed the issue and no more raw exhast fumes smell in my car! drives like brand new now! so get a OEM one dont cheap out and learn the hard way!

[@tonistarks2874]

Eric the Car Guy is a great teacher and very detailed in what has to be done.Keep bringing Eric back for more videos👍🏽

[@bobbyk6585]

Very pleased to see Eric on board and creating content once again.

[@jeremyjay8504]

Eric is a super talented car guru and his video editor is top notch too! Thanks guys!

[@DavidWatson-xb2vh]

Good to see you again Eric! Thanks for putting some more quality concise videos out there. Keep'em comin'!

[@johndesaavedra1040]

I had one instance where the P0420 code came on the heels of other random O2 sensor codes. The sensor was replaced and it has been fine for 50K miles. The history matters most. I agree it mostly points to a bad cat, especially with restriction symptoms. It can't work without flow.

[@Somewhat.Damaged]

Good to see you Eric back in the shop. I'll tell you, his last video in the shop kinda got me a little choked up. Eric, you will forever be my sensei of Automotive Mechanics.

[@Wisconsin4eyes]

The colab I didn’t know I needed. Good to see you again Eric! Be safe, have fun, stay dirty. ❤

[@OleksiyMorozov]

The only cat video on youtube that actually makes sense

[@insanemeddic]

TRQ is a really good source for knowledge and for people wanting to see what they are getting into before starting a project

[@Gomeeze904]

the myth! the legend!! Mr. Eric the car guy!!!!!!!!

[@beerbellybob2989]

I really love and appreciate Eric's videos. The car in this video obviously had problems and needed a CAT. Regarding the P0420 code, I've had a different experience that may help others. My 2010 Subaru Forester, 159K miles, ran great, no codes other than P0420. I researched for days and scanned the O2 sensors similar to what Eric and other channels describe and checked for exhaust leaks. I could not make much of the changing O2 sensor voltages and figured they must be good because they did not trigger any codes. My scanner's (Innova 3040rs) live data function also displays CAT internal temperature (1600F), so I thought it was weird that the CAT was inefficient. I planned to keep the car, and I was determined to fix it. Given the lack of good aftermarket CATs for Subarus and OEM prices from $2K-$4K USD, I decided to replace both O2 sensors (actually front A/F sensor & rear O2 sensor) as a first step- since I'd be buying them anyway when replacing the CAT. Lo and behold, the CEL went off immediately! I used good OEM sensors front: Denso-2349123, Rear: Denso-2344445. Given the price of CATs, and if the car runs fine, maybe a sensor change is worth a try as long as you plan to keep the car. YMMV.

[@jasonjaeger7216]

Stoked on this! Eric you're one of my og car guys on the tube. I've learned a lot from you over the years. Broke me up when you headed out of your place back when. Great to see you here.

[@ObsidianShadowHawk]

Thanks, Eric! I'm glad you're still around. This was a great overview. All these checks are simple enough to do in my driveway before I drop $500 on a new cat.

[@AB-yv9bv]

I’m a fan- this man knows his stuff - great advice - hard to find someone so knowledgeable and thorough-

[@MrSamPhoenix]

It’s great to see and old friend again! Welcome back Eric!

[@technicalwiztv6048]

Listen this I subscribed now because Erick was the first KZbin mechanic channel I watched way back in 2013 nice to see a good mentor again

[@tonybrunetti]

Nice to see you again Eric and welcome back.

[@IBLaZeI47]

haven't seen you in a long while Eric. Welcome back! Great Video Bough myself a IR thermo reader and same issue as what you got in the video. Might be saving $$

[@datsuntoyy]

Nice to know, my Audi cats are a couple grand each. I’m at 140k miles. Any thoughts on Cataclean or other exhaust cleaners?

[@ashishm8850]

I'm a long time fan of ETCG. Glad to see him on this channel 🎉

[@bullgamer7343]

Nice to see Eric again!

[@flex407]

Been following Eric for years

[@kentdavies1988]

We have this code caused by broken exhaust manifold bolts... causing exhaust leak. Causing the sensors the think it was running lean. Fuel trims were way high. Was dumping fuel unnecessarily.... causing fouled plugs and high readings at the cat. Ripped out the exhaust. Welded nuts on the broken bolts. Removed those. Waiting on new headers and catback

[@schigara]

Eric O(South Main Auto) has a very good test for a clogged/restricted cat which is to drill a 1/4 in hole in front and behind cat and insert a 2 inch long piece of steel brake line in each hole and then attach a vacuum/pressure gauge to each and compare pressures. When test is complete, wiggle the brake line pieces out of the holes and weld over the holes.

[@DesignerBrandon]

I got a P0420 code and couldn’t pass emissions. Dealer wanted $4k to replace the catalytic converter. I got some CataClean for $26. After about 100 miles CEL disappeared. I passed emissions later that day.

[@chrismorris1304]

This has been incredibly informative! Let my troubleshooting commence...

[@remix768]

Welcome back Erick… excellent video .

[@ColdWarVet607]

Nicely Done Eric! FYI if you have a MAP sensor in your intake manifold you can use that with a scan tool as an indicator same way Eric used the pressure gauge.

[@Epiz76]

Nice!! Eric is a great addition💪🏽💪🏽

[@IanJAGreen]

Great seeing Eric here!

[@rogergambrel7936]

Thanks for sharing the knowledge Eric appreciate it bud👍

[@gsticks9778]

Dang! So cool to see Eric again!!

[@germandominguez4716]

Nice video and Great to see you Eric

[@fordresurrectionest9556]

Awesome job Eric 👏

[@InsertNameHere.1719]

Could a leak in the exhaust manifold cause a PO 420 as well?

[@steveblankenship5474]

Great video and very informative. My daughter in law’s car did the very same thing (174k miles). She has an Acrua TSX and I was fooled with the transmission being very low in fluid and not having an adequate OBD reader.

[@oldblueshhrchannel1847]

Nice addition to the TRQ videos, welcome aboard Eric!

[@Jaimico380]

I'm glad to see my man Eric again!

[@alecsithong]

Great video. Thanks Eric!

[@gsxellence]

I love this colab Eric

[@ttrapp6303]

Keep it up Eric great move from KZbin to trq

[@LutherBuilds]

This was extremely helpful in me learning how to properly diagnose and fix this. I have a Ford fusion with the p0420 code and I will be looking to replace my cat really soon.

[@HouseCallAutoRepair]

Nice to see you here, Eric! (For the viewers/readers) Rapid switching should NOT occur on an AIR/FUEL Ratio Sensor. Only a traditional Oxygen Sensor operating at or below 1 volt, should switch quickly. AND WEAK O2 heater circuits can cause this too!

[@racakvidovic8882]

Thank you Eric help me to diagnosis P420. Does eng oil burn for long time clogcat?

[@Lobo_cafetero]

We love you Erick!

[@mpsniper933]

Excellent video!

[@onehandyangel6132]

This is a informing video, thank you Eric.

[@yt-user03561]

I currently have a P0171 code for System Too Lean on my 2008 Honda CR-V for the past 6 months and the troubling thing about it is that it is such a vague code that could be for a dozen different things. The vehicle has been running and driving perfectly so there are no obvious symptoms of there being anything wrong. I've had 3 shops and the Honda dealer all try to diagnose it but were unable to find the problem. I have replaced the intake tube, MAP sensor, cleaned out the throttle body, ran fuel and exhaust cleaner through the gas tank, replaced the airfuel sensor and 02 sensor and the check engine light still keeps coming back on in less than a day of me turning it off. I haven't looked into the fuel trim data but it feels like the fuel pump and fuel injectors are running fine as I have no issues with starting, idling and driving and there doesn't seem to be anything clogging the exhaust. Could it be an electrical issue that's causing the computer to think there's a problem even though there isn't?

[@chaseboy225]

My 2014 Jeep Grand Cherokee Laredo with the V6 throws up code P0420 but there's no symptoms tho... no drop in gas mileage and no loss of performance. The first time it disappeared was when I sprayed intake cleaner to remove carbon buildup which cleared the code at first but eventually it came back

[@mylazymood]

What should I replace first if I'm having a misfire (p0307) and a P0420? Maybe about 5-15k miles ago, I had a massive misfire causing my dash to light up showing the traction control light coming up, 4-wheel drv needing service, engine reduce power mode and engine light flashing. it only lasted for minutes and it went back to normal driving. I didn't have the money or the time to get it servied asap, but since then I've been experiencing a rough idel whenever I'm parked or stopped, less engine power, and a need to replace my sparkplugs every month (it's foulded and it smells like coolant). The one thing that I'm impressed is that it still runs well on the highway, same mpg average, and runs almost perfectly well once the sparkplugs are changed. My mechanic says I need a new engine (quoted at $10.5k for remanufactured) and highly advise that its worth it since I would be getting a 100k mile warranty with the new engine. I've been quoted less at $6k-$8k for the engine and labor, but it's still a lot of money. Since my vehicle still drives, I want to know if I should invest my money for a new engine first or look at getting a new catalytic converter in hopes to return to my normal driving experience.

[@jacobtorres2617]

You earned my sub, with ERIC.

[@dylanadkins3491]

I'm glad I watched this video. I don't have any other codes except for a p0420 and no performance issues. After changing the sensor just to be sure I'm fairly certain my catalytic converter is the issue.

[@calebinorio100]

Nice I needed this!!

[@toddshook1765]

Thanks for the step by step diagnosis. I have a 2008 Nissan Titan with 197,000 miles. Getting PO420 code. Now I know how to check with my scan tool. Thanks.

[@linoguglielmo141]

Thanks Eric!

[@BADD400]

Good video Eric just subscribed to TRQ.

[@Ram14250]

Get your own channel back Eric! You're too good for this!!!!!!

[@ifixeditmyself1926]

This was really helpful!

[@tevvsix4321]

@Torq Why do you think some aftermarket performance down pipes (with catalytic converters) throw p0420 codes?

[@salvadorzandoval46]

Tanks friend for your tips

[@lazaropolanco8486]

Good job guys, great video

[@FixingWithFriends]

Given the history at Eric's shop, when he said "protect your investment" I am surprised no comment was made on the topic of anti-theft measures.

[@Fatboy53]

Eric is the bomb. Thanks

[@TRQ]

+@Fatboy53 Thank you! We love empowering our customers and showing how to perform DIY auto repairs with our high-quality auto parts! 1aau.to/m/Shop-TRQ

[@xeropros]

Great video

[@Odin33356]

Thanks Eric

[@jqcbigdog]

Good video thank you sir

[@darwinmonsalve925]

Excellent explanation, first time I hear it in Spanish, I always hear it in English, although I don't understand much, but since it is automotive language I make the effort to understand. But my language is Spanish. So it was great to hear them in Spanish. Thank you. 🎉

[@cameronmorgan0203]

I needed this because I just got a replacement ecm. When I got it put on the next day I started getting the code p0420 when I have a brand new upstream and downstream sensor on my vehicle. It’s something that’s throwing the ecm off for some reason.

[@ugwuekesunday8075]

Thanks alot Eric the car guy.

[@Stockbadger]

Eric the car guy is the man.

[@pantelis241]

Nice one Eric😊

[@Josh1999Josh]

just bought both cats and both o2 sensors for me car, worried the engine might've hurt the cat...my question is, if I am running lean or the car is throwing misfire codes (which it currently is with the bad cats still installed) what are some of the next steps I should take without throwing a bunch of parts at it?

[@wx1618]

Hi Eric. I just installed long tube headers with a catted x pipe on my 14 mustang gt after one day I got codes P0420 and P0430 any idea what made these codes to come out?

[@rockynix7731]

Thanks Eric for the tip ..

[@jimtownsend7899]

I thought I was hallucinating! Eric the Car Guy at TRQ? Kewl!!!

[@christopherlanger3159]

Quick question, is it ready enough to get in there to throw in a non-fouler

[@saga2760]

Do you recommend changing O2 sensors do to milage and or age of vehicle, regardless of engicodes being present? Jus wondering if is a good idea.

[@ditomathew1]

I have a 2009 Pontiac Vibe 2.4L at 230000 miles. I bought it used recently. No Cat codes, but I get a severe hesitation in acceleration just like you have shown in this video. I have two cats and I am thinking to replace the second one which is unmonitored by O2 sensor.

[@knucklehednation]

I've been getting a check engine light with the P0420 code for a couple of months. It comes and goes. The car is a 2006 Prius with about 158000 miles on the odometer. I did catyclean twice. If the code isn't permanent and comes goes does it mean that it's partially clogged?

[@antoniovalencia2001]

Excelente video..

[@davidrobertson3498]

Random question anyone know why changing the 4 tires on my 1990 Acura Integra would cause the check engine light to turn off. It has been on for 4 years and mechanic after mechanic were unable to troubleshoot. Then went to get 4 new tires and bang light is off.

[@atomicdmt8763]

excellent info

[@darwinmonsalve925]

Excelente explicación primera vez que escucho en español, siempre lo escucho en inglés, aunque no entiendo mucho, pero como es lenguaje automotriz hago el esfuerzo en entender. Pero mi idioma es español. Así que fue excelente escucharlos en español. Gracias. 🎉

[@darwinmonsalve925]

Excellent explanation, first time I hear it in Spanish, I always hear it in English, although I don't understand much, but since it is automotive language I make the effort to understand. But my language is Spanish. So it was great to hear them in Spanish. Thank you. 🎉

[@cameronmorgan0203]

I don’t know why this code often comes up on my scanner when I have a brand new upstream and downstream sensor along with a new exhaust manifold!!!!

[@joseduranjr4963]

Eric, my 2017 VOLVO XC60 has the 2.0 supercharged and turbocharged four engine. I too have the PO420 code. Where did you order your catalytic converter from? The Volvo dealer wants $2,377.89 for just the first one where the turbo connects and it’s tiny

[@DavidRamir]

Thank you good job

[@gladysserrano9719]

Good video. I have the same problem (P430) but my car run well. I repair the plug of the inyector of the bank, made a tune up and verified the catalic internaly with a camara and change the upper sensor. I live in Puerto Rico. Here not due all the examination than you do only said change the catalic. The mechanic said than internal material are bad because the age. I have a camry 2004 SE 3.3 with 115,000 milles . The question is, is real than have problem internaly perhaps the car run well? Hector.

[@mckoylach1622]

Thanks for your elaborate diagnostic tips. On the other hand,my 2015 CRV,I had the cat replaced for two months,because of the code P0420,now it’s back with the same code, why ? After market cat or something else ? Thanks

[@rommeltolentino5954]

The causes of P0420 is broken mass air flow sensor gas cap and fuel injection system. P0420 is sometimes is error codes is number one problem.

[@kormitschmiroslav2541]

Very good video how to replace a cat. But I have a question to ask if its clogged why not to fill in 1.5 littres of petrol direct inside to exhaust pipe and run on cold to clean all dirt? I am saying that because saw many videos on youtube. They used petrol, adblue, foam...

[@johnvrba3627]

He’s back

[@arthurfig9614]

Where is located the bank 1 for the Nissan Xterra 2006? Is it the left or right side?

[@bernarddrenzcampbell2757]

I got the check engine light with Po420 code but every time I drive 45min-1 hour on the highway the check engine light goes away for a day or two is it because of city driving?

[@walter.bellini]

Thank you for the video and info Curious question: Shouldn’t the O2 sensors have registered irregularities in it readings, because of the clogged CAT?

[@TRQ]

+Walter Bellini We wouldn't be able to diagnose an issue like that here, you may want to have a local mechanic take a look at it. Thanks for checking us out! 1aau.to/m/Shop-1AAuto-c

[@AnthonyStromDesign]

Can you still have a cat starting to go bad even when it's not throwing a code? The car is sluggish when I accelerate hard on when I'm going about 80 on the freeway and there's a lot of droning noise and vibrations.