P0420 honda accord

Per the Honda Service Manual: 1. "Poor quality fuel may cause this DTC [P0420]". Probably it is unlikely, but you may want to drive for a while (a few tanks of gas) and make sure that the check engine light is still on. Also, it could be that the catalytic converter is marginal and the CEL is intermittent.

3. Subaru & Honda. If you find a P0420 code in your Subaru or Honda, it’s most likely the catalytic converter to blame. It can also be caused by an exhaust leak or a bad oxygen sensor. Check for vacuum leaks or other fuel mixture-related engine codes. Check for any exhaust leaks before the catalytic converter.Repair Information for P0420 Honda code. Learn what does P0420 Honda Catalyst System Efficiency Below Threshold Bank 1 means and how to diagnose p0420 code H...Good luck trying to buy a Toyota, Kia or Honda. These auto brands have the lowest supply of cars available for sale at dealerships now. By clicking "TRY IT", I agree to receive new...P0420 on Some Honda Vehicles. Code P0420 may appear on some Honda vehicles. On a 2013 Honda Accord LX 2.4L, for example, the code appears because of the following conditions: WU-TWC deterioration; Secondary HO2S (sensor 2) line electrical noise overlapped; Secondary HO2S (sensor 2) connector loose connection; Exhaust system change (besides a ...190 posts · Joined 2014. #1 · Jan 3, 2022. CEL came on and I pulled the codes. P0420 permanent and pending got thrown. Car has 137k on it. I bought car new and it was very well maintained. RA has a Denso upstream o2 sensor for $60.2000 Honda Accord: 4cyl..emissions..P0420 Catalyst System Efficiency I have a 2000 Honda Accord 4cyl. The emissions report says that I have tyroublew codes of P1166, P1167, P1164 and P0420 Catalyst System Efficiency Below Threshold (Bank 1).Aug 3, 2022 · About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright ...

3. Subaru & Honda. If you find a P0420 code in your Subaru or Honda, it’s most likely the catalytic converter to blame. It can also be caused by an exhaust leak or a bad oxygen sensor. Check for vacuum leaks or other fuel mixture-related engine codes. Check for any exhaust leaks before the catalytic converter.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.Mar 26, 2019 · I have a 2010 Honda Accord EXL V6. my check engine light will come on, stay on for a day or so, then turn off. The codes that are on are P0420 (confirmed, and pending) and P0430 (conformed, pending, permanent). If I have to replace a cat, do you have any recommendations on after market brands or sites that are up to par but not dealership price ...190 posts · Joined 2014. #1 · Jan 3, 2022. CEL came on and I pulled the codes. P0420 permanent and pending got thrown. Car has 137k on it. I bought car new and it was very well maintained. RA has a Denso upstream o2 sensor for $60.P0420 - Honda Accord The check engine line (CEL) came on and we took it to Autozone to get a free code reading. It was P0420, which turned out to be a very popular code for all Honda Accords. We have a 1999 Honda Accord LX with 140K miles. We called several local Honda dealership and received an estimate of $1K to replace the catalytic ...P0420 is still there, but I guess the CEL burned out LOL... Daughter wants a 2nd gen Mazda 3, and her birthday is next month.. The skyactive engines are solid and they are overall good Japanese cars.. Tried talking her into a 8th gen civic, but she doesn't like the styling, even though it was better equipped. ... Accords: 2008 Honda Accord ...The Code P0420 in a Honda Accord indicates that the catalytic converter is not functioning properly. This can be caused by issues such as an exhaust leak, a faulty oxygen sensor, or a clogged catalytic converter.

2007 Honda Accord @67K miles. Ck Engine light appeared. Took to dealership and diagnostic test showed CODE p0420. WARRANTY 8/80K miles covered the catalytic converter, but was told the warranty DOES NOT COVER THE O2 SENSOR.P0420 doesn't always mean a pre-cat replacement but it will if you ignore it and allow whatever is throwing the code to go unaddressed. And as others have said, the code may disappear but it will come back. ... 2003 Honda Accord EX-L Sedan 3.0L V6 A/T **DECEASED 10/05/2018** 240,000 miles on original transmission! Satin Silver Full …🚨Saattaisit olla kiinnostunut: Obd-vikakoodi: P1621 Opas OBD-Vikakoodi P0420:n selvittämiseen ja ratkaisemiseen. Tässä artikkelissa autamme sinua selvittämään ja ratkaisemaan OBD-Vikakoodi P0420, yleisen ongelman, jonka moni autoilija voi kohdata.Auton toimintahäiriöt ja turvallisuusvaikutukset voivat olla vakavia, joten on …Fuel System Too Rich. P0172 is thrown when the oxygen sensors detect that the air-fuel mixture is too rich. A rich fuel mixture contains too much fuel in relation to air. The A/F ratio for ideal combustion is 14.7 parts air to 1 part fuel (14.7:1). With that in mind, either too much fuel or not enough air can cause a vehicle to run rich.Aug 25, 2020 · 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...You might ask, "What should I check first for a P0420 code on a Honda Accord?" Mavyn GPT could guide you through checking for exhaust leaks or assessing the condition of your oxygen sensors. Consulting a Human Expert. If the issue seems complex, or if you prefer a more hands-on approach, our human experts are ready to assist.

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Have a 2007 Honda Accord SE with 216,000 on it. It has the 2.4. Last week the light came on so I read the codes and got the two in the title. It still had the original front and back o2 sensors in it. I purchased a NTK for the rear and installed it. The p0139 code went away but the dreaded p0420 still is there and after I erase the code it will ...Could have been a lot of things, bad fuel, loose or corroded connection at the knock sensor. Could have been a rodent chewed the wires. You should check the wiring to the knock sensor. What is going on is your O2 sensors are old and about shot and you need to replace them (P0420) and ditto your knock sensor (P0325).This code points to a failing Catalytic Converter. The Oxygen Sensors measure the amount of emissions in the exhaust going into, and then out of the converter. When they see that the converter is not "cleaning" the exhaust enough to meet specs, the Converter is deemed "below threshold" and the P0420 is set.driveaccord.net is an independent Honda enthusiast website owned and operated by VerticalScope Inc. Content on driveaccord.net is generated by its users. driveaccord.net is not in any way affiliated with Honda Motor Company VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, CanadaLearn what causes the P0420 code in Honda vehicles and how to fix it. The code indicates a malfunctioning catalytic converter that reduces emissions control and affects engine performance.P0420 for 2004 EXL 4cyl SULEV auto. This Accord has 190K miles. The code P0420 came up about 3 weeks ago. Bought Ancel's AD410 scanner on Amazon to read it. I've have tried the fuel cleaner and use of different gas station (costco). Somehow, the engine light disappeared for the couple of days, but then reappeared again.

By following these preventive measures and adopting good maintenance and driving practices, you can minimize the risk of encountering Code P0420 errors in your Honda Accord. Remember, a well-maintained and efficient catalytic converter not only ensures a smoother driving experience but also contributes to a cleaner and greener environment.This page is meant to help you troubleshoot the Honda Civic 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. TableThe original part number was 14310-R44-A01 and the replacement (as of some time in March of 2016) is 14310-R5A-305. There is a Honda Service Bulletin that details the repair, and a link has been posted below to the most current version at the time I posted this, which is March 17, 2016. Genuine Honda VTC Actuator - 14310-R5A-305.Sep 1, 2013 · Hi, I have a 2003 Honda Accord V6 coupe. I've had it for a few months, bought it with 118,XXX miles. My cel came on a few months ago with the codes P2195 Rear A/F Sensor Sensor 1 Bank 1 Signal Stuck Lean, P0420 Catalyst system efficiency below threshold bank 1, and P0430 Catalyst system efficiency below threshold bank 2.By July 2008, at 190,000 miles, the P0420 code stayed on all the time and I replaced the converter ($600. online at Majestic Honda + $70. labor at local muffler shop) to pass inspection. I have not seen the CEL on since then. I currently have 233,000 miles on the van. still using the original oxygen sensors.So last February I had the Check Engine light come on my 2007 2.4 4 cylinder Accord. This code was P0420 and after reading online I thought I would replace the cat and the o2 sensor that plugs into the cat. The car had 65k on it at that point. I reset the code and drove the car for about 10,000-15,000 miles no problems.360 posts · Joined 2012. #1 · Sep 22, 2019. Jan. 10/2018: Check engine light = P0420. The shop assessed it to be catalytic converter, replaced with new direct fit cat.converter. O2 sensors deemed fine by shop. Sept. 22/2019: Check engine light comes on today. I used a bluetooth device (Veepeak OBD 2) and found P0420.P0420 code 2001 honda Accord 2.4 was created by chris.canty. I recently bought a 01 honda Accord with a p0420 code dianosed the cat will replace soon on the scan tool the rear 02 sensor is mirroring the front and I have a short term fuel trim of -22 the long term stays around -7 could a bad fuel pump cause this waiting on a fuel guage in the ...Hello, I have a 98 honda accord EX, and my check engine light is with code P0420, and since it has came on the car sometimes jerks a little when II am driving and when taking off. Is the cause of this …The ECL on my 2006 Honda Accord SE 4cyl has been coming on for the past couple of years at the same time of the year - Answered by a verified Mechanic for Honda. ... I get trouble code P0420 on my 4 cylinder,XXXXX Honda CRV, Catalist below threshold Bank 1. It's been about a year since I replaced the o2 sensors which seemed to fix the problem then.

99 Accord V6 Ex Check engine light code P0420 can mean what? LSH99 MEMBER; 1999 HONDA ACCORD; Over the course of the past month my car has been been surging on the freeway, when giving it gas it idled high. If driven for a longer period of time. ... I Recently Bought A 99 Honda Accord Ex With 164,000 Miles. Previous Owner Has Several Records ...

🚨Saattaisit olla kiinnostunut: Obd-vikakoodi: P1621 Opas OBD-Vikakoodi P0420:n selvittämiseen ja ratkaisemiseen. Tässä artikkelissa autamme sinua selvittämään ja ratkaisemaan OBD-Vikakoodi P0420, yleisen ongelman, jonka moni autoilija voi kohdata.Auton toimintahäiriöt ja turvallisuusvaikutukset voivat olla vakavia, joten on tärkeää, että selvität ja ratkaiset tämän vikakoodin.Hello, I have a 98 honda accord EX, and my check engine light is with code P0420, and since it has came on the car sometimes jerks a little when II am driving and when taking off. Is the cause of this …This code points to a failing Catalytic Converter. The Oxygen Sensors measure the amount of emissions in the exhaust going into, and then out of the converter. When they see that the converter is not "cleaning" the exhaust enough to meet specs, the Converter is deemed "below threshold" and the P0420 is set.Honda Accord P0420 Code. The Honda Accord P0420 code is an indication that there is a problem with the catalytic converter on the vehicle. This code is associated with the oxygen sensor, and can be caused by a variety of problems. It is important to identify and diagnose the problem in order to prevent further damage to your vehicle.P0420 is real common code in Hondas. To meet emission standards, Honda seems to have set the trip level on P0420 very low and causing the cursed "intermittent failure" situation. The first thing I would do is reset the PCM (clearing the code) and see if it comes back. Then consider new O2 sensors.About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright ...Plus their labor rates would be lower than the dealer. The P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs ...

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I shortened OCI from the maintenance minder recommendation to 7,500 right away and then to 5,000 miles for the past 10 or so years. About a week after I did my first OCI using Valvoline 0w20 Protect and Restore oil, I got a P0420 code for catalytic converter low system efficiency. I checked my oil and found that it had gone completely dark, so ...Haiiii. I am driving a 2010 honda accord. After a bad jump start my alternator was gone and once I changed the alternator my computer starts to throw up a code p0420. ... Page 11-338 in the 2008-2010 Accord service manual you can download from this site covers troubleshooting P0420. You can try doing some of that troubleshooting before taking ...'99 Accord: P0420 and Sometimes Engine Hesitation & Rough Idling Hey, I have a '99 Honda Accord (4 cylinder VTEC) - Toyota 2001 Corolla question Search Fixya Press enter to search.Feb 21, 2014 · Have a 2007 Honda Accord SE with 216,000 on it. It has the 2.4. Last week the light came on so I read the codes and got the two in the title. It still had the original front and back o2 sensors in it. I purchased a NTK for the rear and installed it. The p0139 code went away but the dreaded p0420 still is there and after I erase the code it will ...The freeze frame data is: 02 DTC that caused freeze frame data Trouble Code P0420 triggered Freeze Frame. Code Def: Catalyst System Efficiency. Below Threshold Bank 1. 03 Fuel System Status Closed loop - using all oxygen sensor (s) as feedback for fuel control. 04 Calculated Engine Load Value 62.0 %.Ensure that your new EGR valve and Honda EGR valve gasket are mounted on a clean surface. The mounting surface could be dirty or contaminated, complicating matters further. OBDII DTC P0401 can occur after replacing the Honda Accord EGR. Using our DIY guide to clean the Honda Accord EGR can help you resolve the P0401 problem. 3.Hello, I have a 98 honda accord EX, and my check engine light is with code P0420, and since it has came on the car sometimes jerks a little when II am driving and when taking off. Is the cause of this …P0420 Code and Fuel Trim. My Accord is the 2006 PZEV version with 92,000 miles. A few days ago I got the P0420 Check Engine Light which stands for Catalyst System Efficiency Below Threshold (Bank 1). Plugged in an OBDII tool and found that my Short Term Fuel Trim is at around 20% when idling and drops to 0 when I increase RPM to 3000.Honda accord 2003 p0420 ho2s seems ex common research connector p0141 sensor o2 downline wire secondary very justanswerMy 2010 honda accord v6 had the following code p0420 how many catalytic 2007 honda accord 2.4l. engine code p0420 showing, can someone help meFix code p0135 honda accord 2001👏👏👍.Here are the most common causes of P0420 in the Honda Accord: Likely Causes. Bad catalytic converter; Bad O2 sensor; Other Causes. Exhaust leak; O2 sensor wiring; PCM issue; Overheating converter (usually caused by a misfiring engine, there should be codes) Burning oil (overheats converter, usually no code) Engine not heating up enough ….

Understanding the P0420 Code. The P0420 code stands for "Catalyst System Efficiency Below Threshold (Bank 1)." It suggests that the efficiency of the catalytic converter is not …The Check Engine Light (CEL) is on, with a code P0420. Tests/Procedures: 1. Verify that the fuel trims are good at idle and when driving the vehicle. It is possible to have the fuel trim at 20% and not set a fuel trim code and cause the catalytic converter to not function properly. 2. If the fuel trim is only off on one bank, look for a faulty ...as a pass smog tech with a bar90 We learned that p0420 indicates that your 02 sensor is getting a high reading of Hydrocarbon (HC) or unburned fuel but at the same time this reading can be a result of a faulty 02 sensor, worst case scenario is a bad catalytic converter. ... 2010 Honda Accord - LX - Polished Metal Metallic - 92k miles - Bought ...A discussion thread about the possible causes and solutions for the check engine light code P0420 in a 2013 Honda Accord LX. Users share their experiences, opinions and advice on the catalytic converter, oxygen sensors and emissions system issues.P0420 Code, RV6 install + ktuner. So I purchased my 2013 honda accord ex-l v6 several years ago. Ended up re-doing the stock exhaust with several of the rv6 parts. Since then I've had no issues out of the car driving it as my daily driver, but last year or so I had an issue with the CEL coming on. It happened when we were on vacation on the ...4198 posts · Joined 2015. #4 · Mar 26, 2021. P0420 has nothing to do with burning oil. It means one of your O2 sensors is reporting that the catalytic converter (cat) isn't doing its job properly. Being that the cat is a catalyst and not a wear item, the more likely issue is the O2 sensor is toast. First replace the downstream O2 sensor and ...As the code description implies, the P0420 code means that the vehicle's Powertrain Control Module (PCM) has detected that the Three-way Catalyst Converter is …Apr 9, 2017 · Plus their labor rates would be lower than the dealer. The P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs ...P0420 definition : Catalyst system efficiency below threshold (Bank 1) Issue Severity: MODERATE – Extended driving with this code can cause internal engine damage. Repair Urgency: Get this code fixed as … P0420 honda accord, First Honda I have ever owned and just purchased as a 3rd car for kids. Has 153k miles and just got the P-0420 code. Plugged in the scanner (See image inserted below), went to live data, and the O2B1S2 sensor was up and down between 0.85 --> 0.15, this sensor is the downstream (after the first CAT just off the manifold) ON the scanner under live data there is also a point called O2SLOC and he ..., Sadly, the P0420 came back on within 50 miles of clearing the code on first trip with highway speeds for more than 5 minutes. So disappointing. In the past, it's usually stayed off for weeks or months after reset. ... 2010 Honda Accord - LX - Polished Metal Metallic - 92k miles - Bought used in September 2012 with 11k miles Wrecked. Save Share., Conclusion. The P0420 code is a generic diagnostic trouble code that indicates a problem with the catalytic converter's efficiency in the exhaust system. It can be caused by various issues, ranging from faulty oxygen sensors to engine misfires or fuel system issues. Suppose you suspect your Honda car has this code., In this video, we're going to show you a quick and easy way to fix your P0420 without having to replace your catalytic converter. This is a quick and easy fi..., On a 4 cylinder, it's the only converter the car has. On a V6,, P0420 would refer to "bank 1" - the converter that is mounted past the exhaust manifold that services cylinders 1-2-3. There are other possible causes of a P0420 code on a Honda. There are some service bulletins related to P0420 codes. Some suggest engine processor reprogramming., The Fleet: Victus - 2012 Honda Accord - EX-L V6 - Crystal Black Pearl - 37k miles - Bought used in July 2022 with 23k miles Bolt - 2006 Honda Odyssey - EX - Ocean Mist Metallic - 110k miles - Bought brand new in August 2006, never any major repairs, possibly the most reliable Odyssey on the road, Sadly, the P0420 came back on within 50 miles of clearing the code on first trip with highway speeds for more than 5 minutes. So disappointing. In the past, it's usually stayed off for weeks or months after reset. ... 2010 Honda Accord - LX - Polished Metal Metallic - 92k miles - Bought used in September 2012 with 11k miles Wrecked. Save Share., I am driving a 2010 honda accord. After a bad jump start my alternator was gone and once I changed the alternator my computer starts to throw up a code p0420. I tried to erase the code and it came up again. I know it's something related to the catalytic converter. But so far i didn't experience symptoms like. Rough idling. Rotten egg smell., Solucionar el código P0420 en un Honda Accord puede ser un proceso que requiere de un diagnóstico preciso y la revisión de varias componentes. Aquí te presentamos algunas posibles soluciones: Reemplazar el catalizador: Si se determina que el catalizador está dañado o ha alcanzado su vida útil, será necesario reemplazarlo por uno nuevo y ..., How to fix you emissions p0420 code for cheap, easy, fast. Watch this video and learn how to turn off you cars check engine in under 10 minutes with parts av..., I am driving a 2010 honda accord. After a bad jump start my alternator was gone and once I changed the alternator my computer starts to throw up a code p0420. I tried to erase the code and it came up again. I know it's something related to the catalytic converter. But so far i didn't experience symptoms like. Rough idling. Rotten egg smell., She's a 97 accord, special edition, Automatic 4 cyl. 272,620k I got the p0420 code when the check engine light came on. I ran a bottle of cataclean and the light stayed off for 550-600 miles. Now the check engine light is back on and I'm pretty sure it's the p0420 code again because I have that sluggish kind of loss of power performance., 3. Subaru & Honda. If you find a P0420 code in your Subaru or Honda, it’s most likely the catalytic converter to blame. It can also be caused by an exhaust leak or a bad oxygen sensor. Check for vacuum leaks or other fuel mixture-related engine codes. Check for any exhaust leaks before the catalytic converter., Go to Honda r/Honda • by ... P0420 (2012 Accord 2.4) I bought a used 2012 Accord 2.4 last February. The old owner said that the cat con on it was missing (since it was in California), and because of that the check engine light could come on at times. The state where I live waives emissions tests, so, I decided it wasn't a big deal., I don't have a Honda Pilot, I have a Honda Accord 2014 Sport, I am also having the codes P0420 (catalyst system efficiency below threshold), 83-11 and 61-11 and was wondering what woul dbe the potential root issues of it and possible solutions Honda Pilot's codes. Mechanic's Assistant: The Honda Mechanic can tell you the exact part you'll need. Would you like any additional help or materials?, A P0420 code is set when the upstream sensor and the downstream oxygen sensor sense the catalytic converter is not doing its job. Basically, the amount of oxygen going into the converter is not being burned, and it detects it through the downstream sensor. Oxygen is the key here. Modern Engine Management Systems leave a little bit of extra ..., Victus - 2012 Honda Accord - EX-L V6 - Crystal Black Pearl - 39k miles - Bought used in July 2022 with 23k miles ... P0420 can be caused by a lot of things, but typically it's either the O2 sensors or the cat going bad. In the case of a bad cat, you would want new O2 sensors to go with a new cat anyway to prevent a poor mixture getting into the ..., 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 specifically. The purpose of the catalytic converter is to break down harmful pollutants created during the combustion cycle. By using fine platinum and gold meshes to filter exhaust ..., 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., The P0420 code indicates a problem with the catalytic converter or oxygen sensors, which can affect the engine performance and emissions. Learn how to diagnose …, 97 honda accord lx 2.2 liter 16 valve sohc not vtec, failed emissions codes p1382 and p0420 catalyst system efficiency below threshold bank 1. front O2 sensor is getting voltage but voltage seems spur …, P0420 Bank 1 Catalyst System Efficiency Below Threshold (Honda Accord) The P0420 code is a generic OBD-II trouble code that indicates a problem with the catalytic converter system. This code is often seen on Honda Accords, and it can be caused by a variety of factors., Codes P0420 and P0430! HELP! Sooo I'm hoping someone can shed some light on my situation. I have a 2000 Honda Accord Coupe, 4cyl manual transmission. I have 208k miles (an oldie but goodie car) I've replaced just about everything on this car and it's still running nicely...aside from the CEL (check engine light) consistently lighting up., Honda Accord Forums. ... P0420 / Bad cat? Jump to Latest Follow 3K views 2 replies 3 participants last post by ElPigto Feb 7, 2010. M. Mulcheese ..., Jan 19, 2024 · Fuel Delivery Issues: Problems with the fuel pump, fuel injectors, or fuel pressure regulator can result in insufficient fuel reaching the combustion chamber. 4. Exhaust System Leaks: Leaks in the exhaust system before the oxygen sensors can cause false readings and trigger the P0171 code. 5. Dirty or Clogged Fuel Injectors: Accumulated dirt ..., Code P0420 is no stranger to Honda Accord owners. It's an indication that something's amiss with your vehicle's catalytic converter. This component plays a vital role in reducing emissions, and when it falters, it triggers the check engine light. Common causes include a faulty catalytic converter, issues with oxygen sensors, and pesky ..., It never did. I just went to auto zone and they said it is a P0420 code -Catalyst Efficiency Below Threshold (Bank 1). They told me that it's the Catalytic Converter. I'm hoping it might be the 02 sensor (s) instead. 2003 Honda Accord V6 EX-L with Navigation. 172,XXX miles., Jan 17, 2024 · Some possible causes for code P0420 in a Honda Accord include: 1. Faulty oxygen sensor: A malfunctioning oxygen sensor can provide inaccurate readings, leading to the P0420 code. 2. Catalytic converter issues: A failing or damaged catalytic converter may not be able to efficiently reduce emissions, triggering the code. 3., 5,852 Posts. #59 · Aug 31, 2013. BTW the Rear O2 sensor is what the computer uses to determine if the Cat is below efficiency. If the computer sees the sensor after the CAT go from rich (over 600mV) to lean (under 300mV) it will set the P0420 code or if it sees no data (or set a P0430 code for bank 2 on V engine)., Hi, I am using Honda Accord 2011 - V6, I got check Engine light on my dashboard, when checked the fault code, I got P0420 (Catalyst System Efficiency Below Threshold Bank 1). I went to a mechanic and he ran some tests, then on Charging Test it showed Excessive Ripple (Volts 12.65 V) and then suggested me to get my alternator changed., Repair Urgency: While a vehicle with a P0420 code can still be operational, it is advisable to address the issue promptly to prevent internal engine damage. How To Diagnose The Cause Of P0420. Step 1: Retrieve Codes with a Scanner Begin the diagnosis by connecting an OBD-II scanner to the vehicle's diagnostic port., I have a 2003 Honda Accord showing engine malfunction codes P0420 and P0141. The light only comes on intermittently, but the codes are always there when I get an OBD-II test. Thinking it was the catalytic converter, I installed a new one I got for $150 at catalyticonverterwarehouse.com. The light was off when I installed it, but came back on ..., P0420 for 2004 EXL 4cyl SULEV auto. This Accord has 190K miles. The code P0420 came up about 3 weeks ago. Bought Ancel's AD410 scanner on Amazon to read it. I've have tried the fuel cleaner and use of different gas station (costco). Somehow, the engine light disappeared for the couple of days, but then reappeared again.