@@rp6236 I would gladly pay someone to check out my truck that knows what they are doing. I want a guy that understands fuel trim’s and all this other high tech garbage. Last guy said 02 censer and that fixed nothing. I would also like someone who knows how to tweak the computer. I haven’t found anyone yet other than part changers. Hell I can do that! I did fix the track control problem. My tires looked good but I you really look closer one was separating. As soon as I pick up speed the one wheel would throw a code. New tires a it never set a code again.
SUBSTANTIAL Sir Pete Meier Motor Age My teacher Thank you Take care and have a great Evening SUBSTANTIAL Sir Pete Meier Motor Age From Nick Ayivor from London England UK 🇬🇧
I’ve been ase cert tech and service manager over 40 years and the only fraud l’ve seen is poor diagnostics and ignorant owners. Most cars and trucks thru the shops l’ve worked have hundreds of thousands of miles with original converters working as designed. Not a perfect system, but the best we have if we want to continue burning fossil fuels. Basic maintenance consistently performed is enough to keep most issues at bay. There will always be exceptions and poor designs and manufacturers.
@@arthursmith1732 So my car is 17 yrs old with clost to 200k miles. The stock cats are no good they have lasted for as long as they could now throwing P0430 and P0431 trouble codes. I'm in California where it is illegal to install EPA cats. Plenty of those availalable but no retailer will sell nor ship EPA cats to Cal. Politicians will only allow approved CARB cats as replacements, none that exist in their database for my vehicle. I spoke with the state emissions rep they said my only option was to junk the car when there is nothing else wrong with it. Many others are going through same issue in my state. I don't see how this is caused by ignorant owners
@@JYAN2852 I knew you were in commiefornia when i saw your first comment! Im also in this ridiculous state and i have been going NUTS trying to get my damn van smogged! Ive scowered the internet looking for the right damn cats and when i finally find some, THEY ARE THOUSANDS OF DOLLARS!!! Thanks a lot gov newscum!! I hate this state cus of that commie bastard! Ive tried cataclean a few times and paint thinner too! Damn light keeps coming on at or before forty miles! Ive put TONS of money into this van and i will be damned if i am gonna scrap it!!
Definitely first step is basic maintenance and spark plugs. Then track down all vacuum leaks. After that make sure o2 sensors are good and finally cats as the last resort.
I got this code after changing spark plugs and ignition coils and driving about 50 miles or so. I've done the replacement twice already with no problem. No misfire codes just p0420 efficiency low bank 1. Any ideas?
@@thejagmohan7121 loose plug could cause it. You used the spec denso or ngk plug? If it wants platinum don't use iridium or vs versa. Some motors like the Toyota 3.4 are super sensitive due to the reverse polarity coils. Hard to know your situation based on the general post
All of these are great tips, but let me tell you my experience. I have a 2013 Nissan Altima S with the 2.5 4 cyl. For several months I was plagued with the P0420 code. My mechanic tried all the usual diagnostic techniques, checking o2 sensors, cleaning the catalytic converter, even going as far as gutting the rear catalytic converter to relieve a suspected blockage. The problem not only persisted, it got worse. Instead of coming on every 150 miles or so, the Check Engine light came back on every 50 miles. I have probably spent around $500 trying to get the stupid light to stay off. You know what finally solved the problem ? As per routine maintenance, I removed and cleaned (I have a K&N) my air filter. I cleaned and re-oiled it according to K&N's instructions and re-installed it. NO MORE CHECK ENGINE LIGHT. After all the hours and all the money needlessly spent, the solution was to clean my freakin' air filter ! Something so basic and elemental, I didn't even think of it. The lesson here ? Check the most basic, cheapest stuff first. You may think you have a special car with a problem so unique, no mechanic has ever seen it before. In all likelihood, its something simpler than you or your mechanic realize.
Save the K&N for the dirt bikes. Use OEM air filters. I put original OEM air filter in my Lexus LS400 and now I'm getting better gas mileage. Switch to the OEM Air Filter and run a can of 44K Platinum by BG in a full gas tank. That got rid of my Check Engine light. My CATs have 278,000 miles on them. I always use 44K and it gets rid of my check engine light for quite a while. I use Chevron gas. My emissions test results way below the limit. Codes P0421 or P0420, OEM Denso O2 sensors.. Lexus tried to get me for $4000 for two CATs Ha Ha Ha Bozos
I had a similar problem. But it wasn’t just cleaning the Canon air filter it was also cleaning the mass airflow sensor. The thing that pisses me off is the three mechanics I took the car to when I was having these issues all they didn’t look at codes and replace parts. That’s what they are parts replacers. They have no clue how to diagnose anything on their own without a computer.
After chasing my tail a number of times trying to troubleshoot a P0420/430 DTC, I would check the manufacture’s list of TSBs and see if there were any software/reflashes that might address the issue. Wasn’t unusual that new vehicles had very tight software constraints to get them certified and keep the EPA happy. After the vehicles amassed many miles through a myriad of conditions, updated programming via reflash gave the ECM a bit more elbow room to keep the MIL off. That “Silver Bullet” saved many of my customers the high cost of converter replacement. signed, One happily retired 35 year ASE Master Technician…
My check engine light hasn't turned off in ten + years. I finally gave up on it. I think they exist to get people to empty their wallets on worries that don't exist.
Just a heads up, injectors on a direct injection engine are under such tremendous pressure compared to port injection. Injector issues on DI engines can actually cause compression issues. If DI injectors are ever removed for any reason, they must be replaced with a new injector to prevent compression issues.
My PO 420 code came on due to a Fram extra guard air filter that I had just replaced went back with original equipment Motorcraft air filter in PO 420 code went away, not saying that there’s not some underlying issue but that’s what removed the code on my 2018 Ford F150, 2.7 L.
experienced an interesting one in regards of this code P0420…it wasn’t my cat at all but rather it was the oil leak that spread under my car due to negligence oil changed my oil guy did…my Hyundai dealer discovered it and saved me $4K of cat repair costs…it was a breath of fresh air after I learned about it
Yup I've seen that happen. Some cars have oil filters located directly above (or close enough) to the upstream 02 sensor and that oil filter can be in a very restricted spot in which you don't have much of a choice but to make a mess when you remove it. When that happens it's very possible for oil to leak/splash/drip on to the 02 sensor and eventually work it's way through the threads and contaminate the sensor. I've seen this mentioned as a common issue in several car threads to the point that many car owners of that particular make/model started doing their own oil changes so as to not have to deal with the P0420 shortly after each oil change. This is also a perfect example of why it's so very incorrect to assume when a P0420 code pops up that it's the cat. The vast majority of times I've deal with that CEL code, I've been able to resolve it other ways. Only once was it a bad cat and that was within the warranty period (luckily) and it was also quite obvious that it was the cat because it sounded like a metal can full of pebbles sliding around under the car when coming to a stop or accelerating indicated a shattered catalyst. But every other time, it was not actually a dead cat and the resolution was usually relatively simple and a fraction of what it would have cost to replace the cat and/or sensors.
@@jludtxs I didn’t clean it myself but I noticed when I brought it to my mechanic and told them about it…they air pressured hosed it underneath with some water and wherever the leak was coming too from the sides
@@keithburningbush6456 Can you elaborate on that? I'm a backyard but capable student. But I don't follow your tweak there. Are you saying they spilled a lot of oil? or something else? Just wanting to learn.
Your theology is correct, but none of you techs ever give what the actual numbers we should be looking for. example: fuel trim @ idle vs 2500 rpm! When they"re out of skew, what to look for! I have a 2007 forenza with -10 in the long term @ idle and short term is zero. At higher rpm it hovers around zero! I"m still getting a po420 after replacing the convertor several times, ecm, spark plugs, wires, coil, injectors, intake gaskets, complete exhaust, and timing belt! The air/fuel ratio is 14.7 so I know its running well! Should I reflash the computer? I don"t know what else to do!
Several years back I followed Scotty Kilmer's advice for a catalyst failure code. Added acetone to a low fuel tank and ran it. The code resolved and never came back.
Looking at the same solution as well, seriously. My new to me '07 Honda Odyssey has become a money pit. I've had a bear of a day and your comment made me laugh, thank you!
I had this code on my Chevy Cruze LTZ. A fresh set or plugs and a new coil pack solved my issue. 170k miles. It was due for a tube up. $200.00 we’ll spent.
@@serchizmit is a threaded pipe that threads into the O2 sensor bung and the sensor is threaded into the end of the pipe. This puts the sensor outside of the exhaust stream helping to have a steady O2 reading on the secondary O2 sensor and avoid throwing a code. On some cars this works and some it won't.
I've read several comments and agree there are several different causes. But, for me, the code is for Bank 1. This means that the side of the engine with Cylinder 1 has an issue. Therefore, it does not seem like common components of the engine are at fault - such as a dirty air filter or MAF. It seems more likely that the issue is related to that side of the engine and it's combustion, oil, gas, adn exhaust components. Has anyone had an experience where the code specifies Bank 1 but it was not necessarily fixed by a component related to Bank 1?
@@YakanAutumn My car has the same, P0420 Catalyst system Efficiency Below Threshold Bank 1. I just saw a video that said to try the Catalyst sensor, so i just bought it and will put it on. Hopefully that will fix that damn ISSUE!!!
From one old man to another, this car mechanic has aged just right; using his experience to not overprice customers and make sure the origination of the problem is cured, not just the symptom.
This is a logical troubleshooting process ... and one I cannot see the typical independent or dealer mechanic spending time on. Two dealership techs independent of each other relied solely on DTC readers -- and incorrectly diagnosed the need to replace both of my 4Runner's cats and related sensors due to severe loss of power. Neither fixed the problem. An independent could not identify the source of the problem, either. Finally, my old-school pre-ECU carbureted background whispred "fuel pump," and I insisted under emergency circumstances that it be replaced even though the dealer tech was very leery. I was right ... but also several thousand dollars lighter in the bank account. Apparently, a bad fuel pump will not send adequate fuel, causing lean codes that seem to DTC readers to be cat-related. The lesson is that typical techs either cannot or will not do the kind of research outlined in this valuable video.
Their is no possible way that I know of for a lean code to be determined as a cat failure. Whoever you took it too either did not know what they were doing or knew exactly what they were doing! Did you receive your old cat back?
@@jeffflanagan2814 No, I did not. Didn't even think to ask. It was a bad situation all-round, but it is fixed now. I the end, I have two new cats with sensors, all new oil-control valves (another misdiagnosis, but they were indeed in poor shape), and a new fuel pump. All this at less than 160k miles, not what one expects with a 4Runner.
In 2018 I took my 2004 Toyota sienna to the Toyota dealer they said it was a bad oxygen sensor I replaced it then it was another bad oxygen sensor I replaced it. Then it was a catalytic converter so I replaced it. Then it was the other catalytic converter! At this point I’ve bitched and complained all you people do is replace parts do you actually know what’s wrong their response was “these are the codes were getting“. The engine check light and VSC light stayed on for three years. Two weeks ago I decided to clean my mass airflow sensor. My lights turned off on the road. I’m thankful the catalytic converter wasn’t the problem but I’m pissed off that it’s supposed professionals had no idea what the hell they were doing!
If your mechanic is not a technician, tread softly. Now days most problems can be determined with a scan tool, oscilloscope, laptop, smoke machine, and fuel pressure guage. Never let a mechanic "try this" or he "thinks it's that". If they cannot explain what your problem is, why it's bad, how they determined or diagnosed the issue, or show you what /why a part needs to be changed. Do not let them work on your vehicle. Don't think we'll the O2 sensor didn't fix it, but it had 100k miles on it anyway it needed a new one. No! Most of the time you are trading a perfectly good working OEM very expensive part designed for your vehicle for an inferior aftermarket part. And it will not last as long, some ECMs will be further confused by the non OEM part and it will say it will work with your vehicle but it might not work very well or cause another problem. A reputable technician will only change the part or parts that fix the problem. Not charge you 5000 for shit you didn't need and keep your good working OEM parts and sell them on ebay or use them on another customers car and charge them for new shit. It's easy to tell who knows what they are talking about. Guys caked in grease, that don't use electronics 1st, are the wrong people to be talking to. Also the tech that works the counter that doesn't turn wrenches and try to upsell you transmission flushes, coolant or brake fluid flushes, air filters without looking at it, don't let them talk you into something you don't need. Most not all dealerships are good. But some are just as bad as jiffy lube who hires anyone to change oil. And sells you filtered recycled used motor oil will do anything to make their commission higher. And ask them if they make commission or hourly wages.
thanks for the great explanation ... there MUST be a better way ... amazing engineering to make a car a car ... but it's WAY too complicated ... and expensive ...
Cat cleaner removed the check engine light on my old lexus. But the VSC ON OFF lights still on (which go on in Toyotas when the check engine light goes on). Any ideas?
In the North East we most commonly see faulty converters. Exhaust leaks will show up in the fuel trim data, if theyre affecting the converter. Exhaust leaks are audible, and traceable in fuel trim data. 95% of the time, its a bad converter BUT the first step is to replace the rear o2 sensor, then the cat if code comes back.
I sprayed down the flex pipe with soapy water and it started to bubble up .I currently have a p0420 code .I’m going to repair the flex pipe and hopefully that will solve my CEL.
Very likely it will. That is letting air in and throwing of what the sensors are seeing and could even cause the cat to overheat because of the leaning out of the feed gasses. Let me know!
2011 Camry le all stock n 390k miles all original parts. Could not go up a hill but flat driving ok. Seems to lack HP too. Never change trannie fluid, so I'm I'm getting code for torque converter n code for shift selinoid. Non of this has to do with emission right? Check light on n off n p0420 for cat was another code. With these Toyotas, the manufacturer messed up as it is known to lose oil. The pcv needs to be replaced to solve this. Since it is leaking oil but not dripping on the ground, the oil goes to the exhaust n can clog the cat. I had a smog ran with co2 being 0 but hc was 15 so it failed emissions. Now getting a new cat would not solve the problem. Maybe I'll pass smog upon getting a new cat n can drive for 2 more years b4 I'm up for another smog. Eventually the new cat will get clog up as well so he's right when he said that the underlying issue needs to be addressed first. Plus with mine at 390k miles, maybe it is time for a new cat or get a newer car. Over 2 Grand just to get a cat replacement with mine. Fixing cost more than the value of the car so why bother? An option is to get cataclean bottle as it may help with the carbon build up n hoping to get that smog pass. California I tell ya. If this was MN where no smog is needed, I can go as high as 600k with this gifted vehicle. Oh n another way to test to see if your cat is good or not is to get a heated thermal laser scanner. You take the reading of the top of the cat, the middle, n the back end. Top should be hot, middle hottest n the back should be cooler. If the Front is the hottest then you have a clogged cat as heat has no way to get out from the backend so it travels to the front n that can do damage to whatever parts there are on the front like header n pump n whatnot to give you an overheating vehicle too.
I just got my 1st Autel today. MK808BT. So far I'm loving it. Just changed a bad ABS module and was able to flash it and fix my abs lights in my town and country 3.8. This 0420 code is all I have left and both 02 sensors are new so I'll be checking out the converter. Awesome video. Thanks
I think the point of the video is that just because a code is thrown for a certain component, that component itself might be the singular issue, having lived it’s long life, and time to be replaced, like spark plugs, ignition coils, batteries, brakes. But more often than not, by a large margin, the actual cause is because of another component which is malfunctioning and it’s symptom is causing a reaction in the component that is represented by that code. You could replace that component every month and still not fix the problem.
I have the code thing. But an expert said he could fix it for under$220. So then I'm thinking that it could be the O2 sensor because my mileage is about 178k and they might go out around 150k or sooner. I saw one for about$170 and the guy said he could fix the problem for $220 so I think maybe that's what he was going to do. I hope that's the problem then I could just do it myself.
Be careful - without performing a proper diagnosis, no one can tell you what they can do to fix it. With the mileage on your engine, it could be a number of possible causes, including the converter. Seek out a more professional diagnostician.
Will aftermarket catalic Be a cause for p0 420 code I have a 2012 bmw 135i and can’t pass smogg it actually had a aftermarket air cleaner aswell Im putting and buying oem parts and see if that will help Any suggestions?
Sorry for the late reply. Look for a cat that is CARB certified. NY and CA require these to be used as replacements. "Universal" cats won't do the trick.
Have the p0420 code on our 2012 honda pilot. Started bogging when trying to accelerate. My 1st guess was bad cat. I was hoping a bad 02 sensor or air filter but with it running crappy im quite positive its the cat. Which really sucks
On a 2006 ford crown Victoria police interceptor I have a PO420 code catalyst below threshold. I smell an exhaust leak, and per the scan tool one sensor is dead, and cat has reached 1650 degrees. Would you say that was enough to damage the cat beyond saving? And I'm taking it the leak gave too much air, this too much temperature? Pleeeeaaaase help! I know you kind of answered my question in the video
Take care of what you definitely know is bad, clear the code and rerun the monitor. It is possible that the cat overheated but the only way to know for sure is to take it off and look through it OR use a thermal imaging camera to look for signs of melted substrate. Yes, air leaks are like excess fuel - either causes the cat to run hot.
being a 00s chrylser guy (with several in my fleet), i'm very familiar with the O2 sensor outputs and their readings on my Autel MS 906Pro. However a friend of mine had the "dreaded" P0420 code pop up on her Honda. The software on the Autel doesn't report Honda's sensors (2013 Odyssey) in the same way, so I was struggling to help her diagnose, is it a bad cat or a sensor problem. Curiously, the MIL went out on its own, and the code was stored as permanent, but not active. In fact, I had to use EOBD to read both sensors, with the downstream in V and the upstream in mA. My educated guess is she has a bad upstream sensor, and not a bad cat. I came to that determination based on comparing the upstream data between both banks, and noted that bank 1 would occasionally be "smoother" than bank 2, instead of roughly tracking the same, and even once go completely flat line at 0 mA. I considered a possible wiring fault, but the fact the traces look like a sensor getting "lazy" or "falling asleep slowly" then suddenly "waking up", makes me lean towards a failing sensor rather than a wiring issue. The downstream sensors would also follow the upstreams in their reporting and graphing. Where would a DIY shade tree home owner mechanic go do to find more information about specific vehicles and their expected O2 sensor outputs and performance.
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 then come back on?
First thing to ask yourself is, "Did my battery go dead or did I replace it?" Sometimes you have to perform a "Drive Cycle" specifically for your car so your computer can run a "Readiness Test."
@@kariniemannfuss9208 You are a prime candidate. Just Google " Drive Cycle" for you vehicle. You could get one from GMC or your mechanic. On my Tahoe I had to let it idle at a specific RPM for a period of time from a cold start with a number of electrical items turned on and drive it a certain way to allow the computer to scan all sensors to know that everything was working properly. The codes switched off and I was able to get the emissions checked. As far as the no start, you'd have to check with diesel forums with your specific issues. Sounds like a computer communication problem. With no power for an extended period of time, the computer might need to be reprogrammed.
Carbon buildup can also trigger Code P0420. My 2014 Jeep Grand Cherokee Laredo threw up the code even tho the o2 sensors and cats were good. So I thought hmmm what if it's carbon buildup? Got 2 cans of Seafoam intake cleaner, followed directions and after it blew all the carbon out the check engine light shut off and P0420 was gone forever
Have an '04 4Runner V6 4.0L. Had 420-430 and 206; cylinder6 misfire. The #6 plug looked oily- Checked compression 175 psi. No loss of coolant or oil. Good compression. Installed new valve cover gasket set. No more 206 code . Still had 420-430- ran a couple of bottles of cat cleaner & one gallon of lacquer thinner through the engine, per "Scotty". No help there. The 4Runner runs like a banshee. Very quick response. No sluggishness. No foul smoke from the exhaust. No issues with exhaust leaks or vacuum leaks. Changed both downstream sensors & added spacers to the downstream o2 sensors. No more 420-430. Passed smog, then I removed the spacers. Ran good for about 2 weeks before the 420&430 reappeared. I will reinstall o2 spacers (also known as spark plug anti-fouler); you can buy o2 spacers on line with out having to buy two 2 spark plug anti-foulers per o2 sensor, then having to drill the outboard fouler to accommodate the o2 sensor. Just buy the spacers on line. they are cheap & install easily. They come from China, so may take3-4 weeks to receive, but they can work. no guarantee, but cheap enough fix & often times does work. If the problem does not go away after I reinstall the spacers, I will buy a pair of new after market cats- For the 4Runner-they are multiple listings on eBay & Amazon. Any reluctance of the seller to ship restricted state (like mine: CA) I tell them it's for my ranch truck, not registered. They will ship it. They want the business~😁😁 There are YT vids on the spacer install and the anti-fouler method. search them out. Some spacers actually have a mini-cat screen in them. Again-they are cheap.
Hey, I have a 2012 kia soul 1.6 standard transmission. I've been having the same code popping up after each part replaced. So far we've replaced the knock sensor, the MAP sensor, all four spark plugs, the upstream and down stream 02, and the p0420 and p0420 p, keeps coming back. I hate to guess but I'm thinking the Cat may need to be replaced? Not sure what to do. Any thoughts?
That is a brilliant way of troubleshooting exhaust leaks! Beats my way of crawling under the running car and running a bare hand around all sides of the pipe/joints trying to feel a leak...or waving a cigarette around looking for the smoke getting distorted (which, since I switched to e-cigs, is a lot trickier 😃)
@GrandpaMunstersMultitrackLab what is the point of having a system diagnosis if it does not diagnose the problem. People pay hundreds of dollars just to have their mechanic guess at what may be wrong. I've been working on cars, trucks, motorcycles, and many other small engines for over 30 years.. I can guess what's wrong,, but that's all it is a guess. We now have cars with all these computer systems and we still only 'Guess'. My truck pops a code saying 'left bank lean'.. some say head gasket, some say, valves, it's the timing chain... I'm too lazy to fix/replace it. But the other two guesses were close.
My 2018 Dodge Journey has the code and Drives sluggish…it always seemed to have since I got it new in 2019. I changed the nasty engine filter. Anyways, this video was helpful in understanding the mechanism of the CC and the code. So begins the “journey “…🤣
Welll...my cat is definitely bad, the cat is running at 380F and right at the rear is at 280F or so, there are no codes, no misfire, no coolant lost, no lost of oil, but the car drives fine for now, but I will get it replaced because I don't like driving with the check engine light on because is a GDI engine. Gets Destroyed Immediately when the check engine light comes on
Cristal clear,very useful info,as you say sometimes a cat issue is tricky to confirm .. best video and explanation about cat issues i see... Keep it up. Greetings from Spain 👌✔️
I just stumbled on your side and I was very interested in what you had to say but your background music is so loud it's absolutely ridiculous! Go back and look at your own video. I shouldn't have to run for my TV controller to turn the sound down because you... period.
Can't tell you how much I appreciate you posting this. Your presentation is professional, and instructions thorough and detailed. Unlike other videos with "quick fixes" that are on par with slapping a band-aid on a gunshot wound, you covered what's most important: the root cause(s). I was able to determine the state of my cat (spoiler: it's failed 😅) before my lunch break was finished. Thank you again for a fantastic break down. I look forward to your future content!
I had my engine replaced. Three days later, the engine light turned on. They checked it twice and they said catalytic converter needs to be replaced. I was told it might came from the bad engine and ruin the cat. It costs a lot to fix it. I used cataclean and the engine light turned off for 3 days but came back on again. They trying to charge me 3500 for it. I can't afford it. Trying to figure out where to take it for a cheaper price
Any success? Cataclean, 1 gal lacquer thinner, Gumout with PEA, point is to clean out cat. Sometimes you have to clean it 2 or 3 times. Then I would clean it replace O2 sensors.
My CEL light shut off on it's own after one day. Freeze frame data from when the code set reported my RPM at 3950 in a low gear. I did recently get distracted and forgot to shift (manual trans). I would have thought the PCM would ignore that. I will do the other checks in the video just in case.
You FORGOT to shift? Really? I've only ever driven manual transmission vehicles and shifting is automatic (no pun intended!). It's about muscle memory, not just remembering to shift.
After watching just a minute of video I disagree. I remember when obd2 was new and we replaced a converter for the code. The Dealer got a call from Ford and they wanted the converter back. He said we could buy some time with new 02 sensors but more than likely the converter has failed. After all the failed converters I saw a converter fixed the concern without any other components to blame. Nice in theory but if the engine isn't missing and doesn't have other codes, the converter will fix it (except if there is possibly a pcm reflash). Cheap converters are a hit and miss. Luckily I've never had the concerns on my own vehicles with many miles on them. I remember when converters first came on F250's and they would usually give out and get plugged when pulling. No concern was ever found. Replace them and go on. Pulling is hard on things.
my 2006 honda civic does have the P0420 code , it is sluggish especially take off and feels like it has power loss, also fuel consumption is very high. so is that most likely a blocked or failed Cat ?
As a "seasoned" auto tech, I have had trouble at times with the P0420/430 codes. Most of the time, it ended up being a bad cat convertor as you can watch the downstream O2 sensor switch as fast as the upstream: This almost always indicates the convertor is bad. I have found air/exhaust leaks to cause it, of course and I have found a similar test: You can use the evap "smoke" tester in the exhaust. This has saved me many times. Also, many aftermarket convertors are made cheaply and not as efficient as the correct factory unit. I've installed these and had the same code reappear. When I finally convince the customer to spring for a factory unit, the problem goes away - Just sayin
In my case had more voltage from altenator and make ECU to read false from O2 sensors the car has 240.000km or 148.800 miles , when fixed ( altenator ) P0420 code gone after some miles , without erase from ECU .
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? 😩
I love your videos very knowledgeable! Learn a lot from you sir! My name is TASHA from USA 🇺🇸. My check engine light reads P0304 a cylinder 4 misfire secondary DTCs, and 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! The Engine Light Has Been Solid For 7 Years. Should I be worried? And can I keep driving like this without risking my health?
We had this code and a mobile mechanic was able to use his professional scanner to show the two banks, upstream and downstream measures, etc. It was very helpful to see this info vs. guessing. We got an OEM cat, replaced only 1 cat of the 4 (thanks 4Runner), and no more code.
I have an 02' Blazer zr2 4.3ltr. Got a new Cat, Rotor, Coil, ECU, Wires, Plugs, etc. My Check engine light came on & got the 0420 code. Exhaust is new also. It showed Bank 1 below temp. threshold. I changed bank 1 02 Sensor & same code came back. I do have another 02 Sensor located on Bank 1 Sensor #2, the 1 just before the new Cat. I'm installing a new 02 Sensor there today. No leaks, etc. Everything I had installed has less than 400 miles. The Cat is a high flow, Flowmaster Cat & the Mechanic Shop said it wouldn't throw a code. Zero power issues. The Truck is running great even with the light on.. I cant even feel it idling at a red light with the AC on!
Unfortunately, that might not be true about the new cat throwing a code. One reason why a few states require cats certified by CARB. What is the code number that you are dealing with?
So I have a P0430 code on my FJ Cruiser, I can make the code go away with an "Italian Tuneup" which gets me through inspection every time however I have grown tired of seeing the christmas tree on my dash every so often so I appreciate these tips in both the video and the comment section. I happen to know the valve cover gaskets leak a certain amount of oil into the spark plug chambers, is it possible this is the ultimate cause of it? I have been building a parts list to replace a lot of the maintenance parts on top of the engine when I do the valve covers and once I have done all of that, if the code persists, I figure I will tackle the air fuel and 02 sensors next, then finally if it continues the Cat will be the last piece of the puzzle. Truck idles and runs like it's brand new so I rather doubt the Cat is actually bad.
I do all of my regular maintenance but got the P0420 code after refilling my gas tank. Thought it was the gas cap, so replaced that. Cleared the code. It came on again several hundred miles after I got low on gas again. I cleared it again. Drove around for a while, checked and even passed emissions. Then 3 days after emissions passed, low tank of gas and code came back on. What is the deal here? My car runs great btw.
Many monitors will not run when the fuel level gets too low. I'm wondering if that is impacting your issue. What is the year/make/model/engine of the vehicle?
