P0420 code hyundai

Definition and Meaning Fixes Hyundai P0420 Diagnostic Trouble Code: Catalyst System Efficiency Below Threshold (Bank 1)Causes of a Hyundai P0420 Code:Heater...

I have a 2016 Hyundai Accent and my check engine light has a P0420 code. I am told I need a Catalytic converter. My question is would that be the rear or the one upfront with the manifold. Mechanic's Assistant: That code indicates a problem with the catalytic converter Is the check engine light blinking or flashing, or is it solid? When did you ...Afternoon, I've got the dreaded P0420 code. Gas mileage has gone down, now only 12-14 around town and used to be 15-17 before. ... Hyundai Forum is a community for all Hyundai Owners to talk and learn all about their favorite subject: Hyundai cars from the Sonata to the Elantra and even the new Kona! Show Less .Sometimes, when you see O2 sensor related codes, fixing those might also fix the code P0420. If the code P0420 is the only code present, visually inspect any exhaust leaks before the rear O2 sensor. An exhaust leak may mislead the O2 sensor and trigger the code. If you find any broken, cracked or disconnected hoses, replace them …If you’re an avid DIYer and a car enthusiast, you may have come across the dreaded “Code P0420” at some point. This diagnostic trouble code is related to your vehicle’s catalytic c...The P0420 code is related to the catalytic converter. When this code appears, it indicates that there is a problem with the efficiency of the catalytic converter. ... See also Efficient Emissions Control: Hyundai Veloster N's System Inspection. Can a faulty oxygen (O2) sensor cause the P0420 code in my Kia? Yes, a faulty oxygen (O2) ...The p0420 code is an important warning signal in your hyundai accent that relates to the check engine light. The code indicates a problem with the catalytic converter, which is responsible for removing harmful pollutants. Several factors can trigger p0420, including a malfunctioning o2 sensor or a damaged catalytic converter.Next time I will need to take my car to a Hyundai Dealer if it comes up. ... I have the p0420 code I had all 02 sensors changed and 1 converter changed!!! Should I ...P0420. Afternoon, I've got the dreaded P0420 code. Gas mileage has gone down, now only 12-14 around town and used to be 15-17 before. It's a 2008 DGC SE with the 3.3 Flex Fuel and about 251,000 miles. I'm the original owner and the Cat has never been changed since new.

How to diagnose code P0420 on a Hyundai Elantra. 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 …P0420 HYUNDAI Code: Meaning, Causes, and Symptoms | OBD2 Codes. P0420 HYUNDAI – Warm Up Catalyst Efficiency Below Threshold Bank 1 . P0420: DIY Repairing Video TutorialThe P0420 code indicates that the Engine Control Module (ECM) has identified a decline in the efficiency of the catalytic converter …The most common fix for P0420 in the Hyundai i20 is a new catalytic converter, followed by an O2 sensor replacement. Before taking your i20 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 Hyundai i20: 1. Check for Other Codes.The most common fix for P0420 in the Hyundai Tiburon is a new catalytic converter, followed by an O2 sensor replacement. Before taking your Tiburon 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 Hyundai Tiburon: 1. Check for Other Codes.P0420 code. Jump to Latest Follow. 601 views 4 replies 4 participants last post by Majestictobil Apr 3, 2024. Majestictobil Discussion starter. 4 posts · Joined 2021. #1 · Feb 11, 2024. I have a 2013 Hyundai accent and I replaced the cat 2 weeks ago because it was throwing a p0420 code and went into a limp mode and it’s throwing the same ...If the sensors were bad, it couldn’t set the P0420. Let’s understand exactly what a P0420 code is. Here’s the definition: P0420 Catalyst System Efficiency Below Threshold (Bank 1). What the code is telling you is that the …

Read more: OBD2 - OBDII Code P0420 HYUNDAI - Warm Up Catalyst Efficiency Below Threshold Bank 1 | Engine-Codes.com ... #5 · Dec 16, 2012. P0420 HYUNDAI Description The catalyst’s efficiency is demonstrated by its ability to oxidize CO and hydrocarbon emissions. The Powertrain Control Module (PCM) compares the output …P0420: betydning, årsager, reparationer. P0420 kode tydning. P0420 fejlkoden ndikerer at katalysatoren ikke fungerer effektivt og sædvanligvis, at den skal udskiftes. Hvis det genereres, skal du få udført en diagnose af din motor og brændstofindsprøjtning, tænding og udstødningssystem. Årsager til fejlkoden P0420.If you’re an avid DIYer and a car enthusiast, you may have come across the dreaded “Code P0420” at some point. This diagnostic trouble code is related to your vehicle’s catalytic c...We may earn a commission for products purchased through links on this pageP0430 Hyundai Code - Warm Up Catalyst Efficiency Below Threshold Bank 2 - Code Popularity: 49,884 Views - Repair Importance Level: 2/3 - Repair Difficulty Level: 2/3. Table of contents. Created and updated by William Orellana on Aug 20, 2020. Possible Causes; Tech Notes;

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The Hyundai P0011 code is a diagnostic trouble code (DTC) that indicates an issue with the Variable Valve Timing (VVT) system in your Hyundai vehicle. It is important to address this code promptly to avoid potential damage and ensure optimal performance. Let’s dive into what the P0011 code means, why it should be taken …The P0420 code indicates that the Engine Control Module (ECM) has identified a decline in the efficiency of the catalytic converter on Bank 1. This could be attributed to a malfunctioning catalyst or potentially be a false alarm triggered by a defective O2 sensor.The code was P0420. I took it to Meineke, and they replaced the catalytic converter, as well as two oxygen sensors and two O2 sensors (this is according to the invoice also). It was fine for the last almost seven months, and then two days ago, the check engine light came back on with the same P0420 code. Parts and labor are warrantied for a ...Feb 2, 2021 ... ... P0420 error code include: Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required. Use a scope to diagnose ...Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first. ⚠ Check if your Hyundai have Safety Recalls.

13 posts · Joined 2020. #1 · Sep 26, 2022. Hello everyone, I have 2012 Hyundai Accent and been receiving the P0420 code few times. It stays on for 2-3 days and then goes out automatically. I have noticed the code comes back after driving on a very hot day or after driving aggressively.The P0420 code indicates that your vehicle’s powertrain control module (PCM) monitors the poor efficiency of the catalytic converter at Bank 1. This code may also be triggered due to a bad catalyst or a false alarm caused by a faulty oxygen sensor at Bank 1. Basically, Bank 1 and Bank 2 are the two sides of the engine.Hyundai dealers, corporate reps, etc, please message the mods about an official flair. ... 2013 coupe check engine light p0420 code help upvotes ...2017 Hyundai Accent Code P0420. Hello, and thanks in advance for your time! I recently got a CEL on my 2017 Hyundai Accent with 140,000 miles that came back as P0420 “Catalyst System Efficiency Below Threshold (Bank 1).”. I did some research online and the results varied from "It could be many different things don't spend your money on a ...2007 Hyundai Santa Fe. Check engine light is caused by P0420. Troubleshooting tips.Scan tool: US: https://amzn.to/3QYEACrCanada: https://amzn.to/3WvrEVM .Th...Apr 3, 2021 ... Catalytic Converter Efficiency Below Threshold: Code P0420 & P0430 Diagnosis and Repair · Comments799.My car is Hyundai Accent 2017 and has P0420 code check engine light. It has been going on with p0420 code and car runs normal without any issues. It’s drivable. Is it really dangerous for me to operate my vehicle if check engine light is on with p0420. I live in Virginia where they don’t have emission testing.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 …The P0420 code in the Hyundai Elantra refers to a diagnostic trouble code that indicates a potential problem with the catalytic converter. This code specifically …Code P0420 means “Catalyst system efficiency below threshold (Bank 1).” Driving long-term with this code can cause engine and exhaust system damage. The most common cause of P0420 is a bad catalytic converter, but it can also be caused by other issues, such as a faulty oxygen sensor, a rich or lean running condition, or misfires.Honda. In Honda vehicles, the P0420 code is not uncommon. Common culprits include deteriorating catalytic converters and oxygen sensors. Regular maintenance and prompt repairs can help resolve the issue efficiently. Ford. Ford vehicles may also experience the P0420 code. Exhaust leaks, failing catalytic converters, and …Hyundai Models. Elantra & Lantra Forums. MD (2011-2016) Elantra sedan/coupe. 2014 Elantra P0420 Code. 1213 Views 6 Replies 4 Participants Last post by Propflux01, Jun 16, 2018. B. breakinglink Discussion Starter · Jun 14, 2018. Add to quote; Share Only show this user. Hey all! If this is in the wrong forum, let me know so I can …

I've replaced the entire exhaust system now twice on my 2013 Hyundai Accent SE Hatchback.. There are no exhaust leaks anywhere along the system. I drove it a little over 2000 miles and again I get P0420 code.

If the frequency ratio of front and rear HO2S is higher than threshold value, the PCM determines that a fault exists and the P0430 code is stored. Possible symptoms. - Engine Light ON (or Service Engine Soon Warning Light) P0430 Hyundai Description. The catalyst’s efficiency is demonstrated by its ability to oxidize CO and hydrocarbon ...This page is meant to help you troubleshoot the Hyundai Santa Fe P0430 trouble code. It covers the P0430 code's meaning, symptoms, causes, and possible solutions. P0430 is an emissions-related trouble code and is virtually never a breakdown risk. ... If the code changes to P0420, that would indicate that one of the O2 sensors is …Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first. ⚠ Check if your Hyundai have Safety Recalls.The code was P0420. I took it to Meineke, and they replaced the catalytic converter, as well as two oxygen sensors and two O2 sensors (this is according to the invoice also). It was fine for the last almost seven months, and then two days ago, the check engine light came back on with the same P0420 code. Parts and labor are warrantied for a ...I have 2012 Hyundai Accent and been receiving the P0420 code few times. It stays on for 2-3 days and then goes out automatically. ... Hyundai Forum is a community for all Hyundai Owners to talk and learn all about their favorite subject: Hyundai cars from the Sonata to the Elantra and even the new Kona! Show Less .Code P0420 is a common trouble code for catalytic converter efficiency. Learn what causes it and how to fix it on Hyundai Forums, the online community for Hyundai owners and enthusiasts.Decoding the P0420 Code: Bank 1 Catalyst System Efficiency Below Threshold. The catalyst system efficiency below threshold is tech speak for "Hey buddy, your catalytic converter is slacking on cleaning duty." This troublemaker of a code pops up when your car's brain (aka your cars computer system) senses that the cat isn't filtering those ...Hello, I have a 2013 Hyundai Veloster base; odd is 155K miles now, and the warranty doesn't work. My car won't accelerate, and I got these errors; P0420 Catalyst system efficiency below threshold bank1; P0090 fuel pressure regulator 'A' control circuit/open; P0091 Fuel pressure regulator 'A' control circuit low; P2191 system too lean …Causes of a Hyundai P0133 Code: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)The P0420 code indicates that the Engine Control Module (ECM) has identified a decline in the efficiency of the catalytic converter on Bank 1. This could be attributed to a malfunctioning catalyst or potentially be a false alarm triggered by a defective O2 sensor.

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What could cause the check engine light with code P0420 on a Hyundai or Kia? The check engine light with code P0420 on a Hyundai or Kia could be caused by a faulty oxygen sensor or catalytic converter. If the downstream oxygen sensor is functioning fine, the issue may point to a bad catalytic converter that needs replacement.Does Cataclean really fix a P0420 / P0430 error code and catalytic converter. Cataclean Link: https://amzn.to/33t8RVQ Second channel for easy to follow Home ...Now my stuttering upon FIRST acceleration is back again. My fuel economy is also poor at ~14 in the city doing short runs, but still a decent ~22 doing highway only miles. This morning I checked my codes again and now I have P0420, P0455 (Evap Emission Gross Leak), and P0442 (Evap Emission Small Leak) codes. Now I assume that the …Causes Of P0420 Hyundai Code The p0420 hyundai code is an indication of an issue with the catalytic converter. There are numerous reasons why this code might pop up. Faulty oxygen sensors, misfires, vacuum leaks, and exhaust leaks are just a few of the possible causes. Another factor that has an impact on the catalytic converter, is fuel additives.Jul 27, 2019 ... I picked up a new daily driver and it came with a check engine light. This light was displaying a "P0420" code. Ths code ... HYUNDAI P0420 CODE | .....P0430 Hyundai Code - Warm Up Catalyst Efficiency Below Threshold Bank 2 - Code Popularity: 49,884 Views - Repair Importance Level: 2/3 - Repair Difficulty Level: 2/3. Table of contents. Created and updated by William Orellana on Aug 20, 2020. Possible Causes; Tech Notes;10 posts · Joined 2007. #1 · Nov 8, 2013. Hi guys. I recently got a diagnostic computer check on my 2005 Hyundai Elantra 4DSD that has over 95,000 miles and got the code P0420 showing the following: 1. Catalytic converter defective due to. 2. Engine misfire or running condition. 3.That usually means a failing converter, but it's a part covered by federal emissions for 8 years/80k miles. If you live in California it could be longer. If you are still under 80k miles I would take it to the dealer since the parts would be covered. This is an older thread, you may not receive a response, and could be reviving an old thread.How to diagnose code P0420 on a Hyundai Elantra. 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 …Intermittent P0420 code. Was driving last weekend in the mountains (Lake Tahoe -> Yosemite -> Mammoth Lakes) on my 2019 Hyundai Ioniq Plug-in hybrid. Car has about 35k miles. Got check engine light while slowly driving on an unpaved road. When came back to my hotel, checked the code (have an OBDLink bluetooth dongle), it was P0420 - …767 posts · Joined 2017. #2 · Apr 12, 2018. Warm Up Catalyst Efficiency Below Threshold Bank 1. Possible causes: - Catalytic converter deterioration or malfunction. - Exhaust system leaks. - Loose front or rear HO2Ss. - Faulty front heater O2 sensor. - O2 sensors harness is open or shorted.Here’s a good P0420 diagnostic order for the Hyundai Santa Fe: 1. Check for Other Codes. The first thing you want to do when trying to fix P0420 in the Santa Fe is to verify there aren’t any other trouble codes. Three types of codes can give clues as to what’s going on with your vehicle. Misfire Codes. ….

Many factors can cause the car computer to register DTC P0420 on Toyota or any car model. This makes it challenging to diagnose and fix the problem. Engine running rich or lean. Malfunctioning upstream or downstream oxygen sensor. Leaking fuel injectors. Lousy catalytic converter. Lousy engine coolant temp sensor.How to diagnose code P0420 on a Hyundai Elantra. 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 …I have a 2019 Hyundai Tucson with a 2.0L GDI (no turbo) About 6 months ago, after a road trip of about 700 miles, the P0420 code came up, car was at 55k miles. I thought it was a fluke and cleared the code. 6 months and 3000 miles later, the code came back. This time, I did more digging and looked at the data from the vehicle.Got a P0420 code and bit the bullet and had the cat replaced. 6 months later? P0420 code. ... Hyundai Forum is a community for all Hyundai Owners to talk and learn all about their favorite subject: Hyundai cars from the Sonata to the Elantra and even the new Kona! Show Less .HYUNDAI Fault Codes DTC - Solaris, Accent, Santa Fe, Tucson, IX35, Starex, Elantra, Getz, Porter, Sonata. ... P0420 Code P0420 appears as a result of low catalyst throughput. If the device itself is whole, then the combination 0420 may be due to the use of low-quality fuel or the failure of the second oxygen regulator. To fix the problem, the ...If the code changes to P0420, that would indicate that one of the O2 sensors is bad on the bank 2 side. Conclusion If there are no codes other than P0430 present, and the O2 sensors are recording data properly, it’s likely your Hyundai Tucson’s catalytic converter has failed, which is what this code is reporting.Hyundai dealers, corporate reps, etc, please message the mods about an official flair. ... 2013 coupe check engine light p0420 code help upvotes ...2008 hyundai accent runs rough P0420 code. co0de p 0420 refers to vat converter bank 1 below threshold ===causes ---cat converter---wiring ---HO2S ( heated oxygen sensor in the exhaust manifold bank 1 before the cat converter) you have possible 2 problems. 1--- the HO2S is faulty but that alone will not result in what you describe.Hyundai is a popular car brand in the United States, and the mid-sized Accent is one of their top sellers. Hyundai Accents come equipped with factory radios, but if you're an audio... P0420 code hyundai, The P0420 code in Hyundai Veloster refers to a malfunction in the catalytic converter efficiency. This code indicates that the catalytic converter is not working as efficiently as it should be, resulting in increased emissions. One of the most common causes of the P0420 code is a failing or damaged catalytic converter., Ok, I have a 2004 Hyundai Elantra that I bought used 8 months ago. It has just over 72,000 miles on it and the check engine light came on. I took it to Checker's and they gave me the P0420 Catalyst System Efficiency Below Threshold (Bank 1) code. I asked for the english version and he said O2 sensor or Cat and reset the code., Does Cataclean really fix a P0420 / P0430 error code and catalytic converter. Cataclean Link: https://amzn.to/33t8RVQ Second channel for easy to follow Home ..., The code was P0420. I took it to Meineke, and they replaced the catalytic converter, as well as two oxygen sensors and two O2 sensors (this is according to the invoice also). It was fine for the last almost seven months, and then two days ago, the check engine light came back on with the same P0420 code. Parts and labor are warrantied for a ..., I bought a new front pipe assembly (Hyundai calls it a "muffler", p/n 28610-4D100) and installed it a couple of weekends ago. Code has not returned. We see P0420 a lot at work and always look for a bad flex pipe. A local exhaust shop can weld in a new pre-fab flex pipe section and it's a lot cheaper that buying the whole pipe ("muffler") assembly., Some see the weak sales as just a passing phase. Nitin Kumar, a young automobile salesman in South Delhi’s Lajpat Nagar, isn’t having the best of days at work. Customer footfall at..., I've got a 2016 Hyundai Accent hatchback 1.6L, and I've had the worst time with this P0420 code that has came on. It says Catalytic efficiency bank 1, and I'm not sure what to do to fix it. I've heard the Cat lasts like forever, so I'm hesitant to just replace it without finding the underlying issue., P0420: Inefficient Catalytic Converter(s), Defective Front or Rear Oxygen Sensor(s), Misfiring engines: P0430: ... For more information on Hyundai OBD-II trouble codes, contact us today at 855-757-3265 to speak with one of our knowledgeable service teammates, or schedule a service appointment with our online form. ..., GET FIXD. What Does Code P0420 Mean? P0420 definition : Catalyst system efficiency below threshold (Bank 1) Issue Severity: MODERATE – Extended driving with this code can cause internal engine …, This page is meant to help you troubleshoot the Hyundai Veloster P0420 trouble code. It covers the P0420 code’s meaning, symptoms, causes, and possible solutions. P0420 is the most common OBDII code and is virtually never a breakdown risk. A failing oxygen sensor or bad catalytic converter are the most common causes of P0420. Table of Contents, 76 posts · Joined 2021. #1 · Mar 23, 2022. Like the title says my Veloster is throwing the P0420 code every so often. It kinda comes and goes, like I'll clear it and after like a week or two (sometimes longer or shorter) it comes back. I'm worried it might be the catalytic converter, but I'm not getting any weird smells or sounds, no rough ..., 2015 Hyundai Tucson 2.0 P0420 My car started throwing the P0420 code which is almost always a bad cat that needs to be replaced. I had my mechanic put in an order for a universal cat to replace my oem buy I stopped him because I noticed O2B1S1(Upstream) did not have a voltage reading but O2B1S2 did., When the P0420 code appears, the catalyst system efficiency is below the threshold for a particular engine bank, often referred to as Bank 1. This code is related to the vehicle's catalytic converter and oxygen sensors. The primary purpose of a catalytic converter is to reduce harmful emissions from the engine by converting toxic gasses, such ..., Hyundai karaoke discs are programmed with music, video and scrolling lyrics for playback on a karaoke machine connected to a TV or monitor. These discs can also be played on a comp..., I've got a 2016 Hyundai Accent hatchback 1.6L, and I've had the worst time with this P0420 code that has came on. It says Catalytic efficiency bank 1, and I'm not sure what to do to fix it. I've heard the Cat lasts like forever, so I'm hesitant to just replace it without finding the underlying issue., JOIN GASDIESEL GARAGE AS WE DIAGNOSE AND REPAIR THE MOST COMMON CHECK ENGINE LIGHT TROUBLE CODE P0420 Catalyst Efficiency Below Threshold Bank 1 SENSOR 2 ON..., Pesky P0420 Keeps Returning. I have a 2005 Hyundai Elantra GLS that keeps throwing a P0420 code. No other codes just the P0420. Vehicle has 147,000 miles and runs great. Getting 30 MPG even with the P0420. Plugs and wires only have 28,000 miles on them. No exhaust leaks anywhere., Definition and Meaning Fixes Hyundai P0420 Diagnostic Trouble Code: Catalyst System Efficiency Below Threshold (Bank 1)Causes of a Hyundai P0420 Code:Heater..., It’s an aftermarket cat I bought for $200. Even got a new oxygen sensor for upstream that was $160 new. That may be the issue. I know the Hyundai cat is pretty expensive. I replaced the catalytic converter last year in September and it fixed my P0420 code up until now today I have a check engine light for the same code…., P0420 code and O2 Sensor replacement. So my 2003 Elantra has been getting horrible gas mileage, running super rich. I had a constant P0420 catalytic emissions code and one misfire reading. I'd clear it and it'd go away for about an hour and come back. I feared I would have to replace my whole exhaust manifold/cat part until I read this …, GET FIXD. What Does Code P0420 Mean? P0420 definition : Catalyst system efficiency below threshold (Bank 1) Issue Severity: MODERATE – Extended driving with this code can cause internal engine …, The P0420 code in the Hyundai Elantra refers to a diagnostic trouble code that indicates a potential problem with the catalytic converter. This code specifically …, Feb 2, 2021 ... ... P0420 error code include: Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required. Use a scope to diagnose ..., Does Cataclean really fix a P0420 / P0430 error code and catalytic converter. Cataclean Link: https://amzn.to/33t8RVQ Second channel for easy to follow Home ..., This page is meant to help you troubleshoot the Hyundai Veracruz P0430 trouble code. It covers the P0430 code's meaning, symptoms, causes, and possible solutions. P0430 is an emissions-related trouble code and is virtually never a breakdown risk. ... If the code changes to P0420, that would indicate that one of the O2 sensors is …, I've got a 2016 Hyundai Accent hatchback 1.6L, and I've had the worst time with this P0420 code that has came on. It says Catalytic efficiency bank 1, and I'm not sure what to do to fix it. I've heard the Cat lasts like forever, so I'm hesitant to just replace it without finding the underlying issue., ToddF0X Discussion starter. 5 posts · Joined 2016. #1 · May 2, 2016. I have a 2014 sonata GLS with the 2.4L and 26,000miles on it. A couple months ago I got a check engine light for P0420. Cleared it twice and it came back on both times. My gas mileage dropped as well. Called the dealer and they ordered a new catalytic converter and …, 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..., Hyundai OBD II P0420 Trouble Code. The Hyundai Elantra, Santa Fe, Sonata, and Tucson can all exhibit P0420 codes. Hyundais tend to have less efficient converters than other makes, leading to more failures. Expect to replace the converter at some point to clear P0420 permanently., 2013 Hyundai Accent 255K miles. Runs great, still gets around 35 MPG. 40K miles ago I was having trouble with 420 code. Did usual tune up stuff and both O2 sensors. Ended up replacing the Cat with an aftermarket from Eastern Catalytic. I noted that the old one had no carbon or scale, I've seen very nasty Cats before., Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first. ⚠ Check if your Hyundai have Safety Recalls., Here are some steps to fix a P0420 code Honda Accord. First, remove the O2 sensor and pour 4-6 ounces of seafoam into the opening, replace the sensor, and leave it overnight. Reset the code and then continue driving. Increase the gap between the oxygen sensor and the converter using a spark plug non-fowler., This page is meant to help you troubleshoot the Hyundai Accent P0420 trouble code. It covers the P0420 code’s meaning, symptoms, causes, and possible solutions. P0420 is the most common OBDII code and is virtually never a breakdown risk. A failing oxygen sensor or bad catalytic converter are the most common causes of P0420. Table of Contents