Check Engine Light? Smelly Exhaust? How to Diagnose Catalytic Converters

1aau.to/h/ck8/
Flashing check engine light, codes p0420 or p0430, rough running, bad acceleration, or stinky smelling exhaust are all indications that there is a problem with the catalytic converter in your car or truck. But what is the problem? What does the catalyst do? In this video, Andy shows you, and offers some tips and suggestions for what you can do to handle a problematic catalytic converter.
Check out this playlist for more great diagnostics:
• Driveway Diagnostics!
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⚠ DISCLAIMER:
While 1A Auto 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. 1A Auto 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.

[@1AAuto]

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[@isrealperez9069]

I've noticed that you're the only one on KZbin that actually explain what the efficiency really means instead of saying couple words and trying to figure out myself I'll try one more test before I can determine if it's a bad catalytic converter thank you for your information video it was very helpful

[@bonfacemasharia5843]

Isreal, you're right,this guy is rather,way toooo good 👍

[@guesswhomartin9249]

Thank you. You are one of the better teaching I've seen on this topic. Thank you again.

[@GuitarRocker123]

Give this man a raise. He rules.

[@badardujja8]

Hi you have a very nice and polite way of detailing things, i have got Honda Civic 2002 automatic, i don't drive much, only once in a week. it has the same issue, exhaust producing smelly black smoke and sure the fuel average is all disturbed. Need your opinion. Huge thanks in advance

[@wilmerrodriguez653]

Thanks!!, this is exactly what my 2006 honda odyssey is doing.

[@theredlatino4930]

So is mine, how many miles did yours start doing this at?

[@jeffs4760]

Great video. What if you dont have a CEL but I have the P0421 & P0431 codes? The car runs great and no smell. The codes are stored I guess? How do I get them off? I clearde them and I'm going to run through a drive cycle and take it back for smog after I check the scanner again

[@mayowaodus6310]

By hollowing the cat out can this cause a rough idling for about 5secs upon cold start on an LE5 eco tech engine as seen in Chevrolet Captiva 2011(i4)

[@williamphifer5056]

Thanks for the information on the Cats and the O2 sincers... Excellent communication skills🌟🌟🌟🌟🌟

[@1AAuto]

+William Phifer Thanks for the feedback!

[@dga5396]

You said everything looks ok under the hood, can you explain in from 0:34 looks like a bird next or pine needles in that area? Thanks for the video.

[@RyanFordFJB]

So I have a 1994 chevy cavalier rs I have no engine codes and replaced everything to do with cooling (radiator was cracked) before I changed it the check engine light would randomly come on and kick the rad fan full blast all the time until the car is shut off. Then the light goes away. Sometimes its comes on and sometimes it doesn't? Each time it does it only kicks the radiator fan on. I've checked the wiring and changed the fan relay

[@lucasjs1207]

i have a 07 G6, i think the catalytic converter is disintegrated. it sounds like sand when i bang on it, rattle on startup, and bad smell while in the cabin. I have a code p0420 and misfire code p0300, but the vehicle has perfect fuel trim no rich or lean condition. can a bad/disintegrated cat cause a misfire?

[@baldonguyen5095]

I have v6 tundra, can't set catalytic monitor, no engine light, it has front and rear catalytic, front one tempurature inlet is 350, outlet 500, the rear catalytic is 325 for both inlet and outlet, is that normal?

[@juanlopezjr6756]

I've used cataclean and still have issues when I take off motor stutters I hot the same code what other options do I have before replacing the converter?? Ty

[@michellebrothers694]

Gm why would my ford taurus 2013 begin humming when the ignition is turned on after having internal waterpump changes

[@39FORTYWATER]

Can fuel injectors make cats code continue to pop up for emissions inspection?

[@martisewashington3898]

I love all ur videos 1Aauto is very smart and knowledgeable

[@1AAuto]

+Martise Washington Thanks for the feedback!

[@maximobautista9671]

Hi can you answer my question. I have a code P0430. But not smell like eggs 🥚. What do you recommend to check. I changed the intake manifold gasket. And the 2o sensor. B2. S2 And light come up next day. With the code P0430 well it was before with the lean codes. Any advice. Please.

[@shanebryan8151]

Thank you

[@solarpunk3965]

Hi, I have P0420 code, Does loose catalytic converters cause this code popped up also are they suppose to loose or intact?

[@ErnestoDiaz-uy1hz]

Good information. 👍

[@user-py8xw5bk1s]

Perfectly explained

[@1AAuto]

+20 20 Thanks for checking us out! 1aau.to/m/Shop-1AAuto-c

[@todaysupdate6824]

Hi, my check engine light on today . It say catalytic converter defect . But I have change it one month ago . Anyway I erase the code and check engine light gone . So my question is will it come back again. If so how long it will take to come back. Thanks Golf 5 ( 2008 ) 1.4 patrol engine I drove with bad kat about a week but no engine light on and after I drove another week without Kat no engine light on . When I change my both Kat and drove 500km not engine light. Then I put fuel injector cleaner and drove another 150 km . And after engine light on and it says on my obd2 Kat defects

[@Johnthebarber310]

I have a lexus gs350 2007 but the car runs fine I ride it hard & only have an egg smell a few times. I have a P0240.can u tell me what its most likely

[@FaisalAhmed-kf9yf]

1:40 would that coz the car overheating? have check engine light on too, LS400 97

[@carlorocky]

Hello again! Hypothetically speaking, if someone were to hollow out their cat. would the oxygen sensor cause the engine to run badly or run too rich to the point of cleansing the bearings? Thank you!

[@peppytrabonco]

I have the smelly sulfur smell and white smoke from exhaust. I also have 210 compression from cylinder 6. Are they both related or do I have to do valve clearances and clean my cat converter?

[@willsrestorations]

210 PSI at cranking for compression test is extremely high and the Mac should be no more than 200 and even that's high. You have way too much cylinder pressure.

[@sparktechsparkteck2161]

hi i have a polo classic 98 model low idle low power how can i test a clogged exhaust at home dont know where the oxy sensor location

[@7curiogeo]

I find it is crazy that since epa rules, vehicals are subject to very minor failures that add up to major failures.

[@1212LeoSnake]

What about a p2272 error code after you changed the bank 2 downstream oxygen sensor?

[@eggbert191]

I dont have an engine light or rotten smell but I have exhaust smell in the vehicle on start up for a few minutes. 2011 escape. Any suggestions?

[@khalilt6508]

I know I’m a year late but catalytic converters don’t work until the exhaust is fully warm so that’s probably why

[@saifaldeenhashim3544]

Hi i replace the catalytic manifold on my 2013 ford explorer with aftermarket part but after I replace it the engine shaking when I run the car and drive it to 30 to 40 I get shaking and fell the car try to turn of or miss fire is this because the aftermarket catalytic or something else? Thanks so much

[@1AAuto]

+Saifaldeen Hashim 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

[@tacticalpickle7]

Hello. I have a rotten smell come from the exhaust pipe and rough idle found vacuum leaks got those fixed replaced EGR valve still nothing replaced idle control valve do to vacuum leaks also the throttle body gasket still nothing the only one code I have now is a P0406 …. Engine runs very rough Need help --04 expedition 5.4 motor

[@williamsolomon602]

1A, I HAVE A97 740I M MODEL, MY MECHANIC SAYS IT'S GONNA COST 3400 FOR NEW CATS FROM GERMANY,CAR HAS NONE OF THE SYMPTOMS U GUYS ARE TALKING ABOUT AND IT HALLS ASS WHEN I GIVE IT ⛽ GAS, CHECK ENGINE LIGHT HAS BEEN OFF ABOUT MONTH (BEEN USING TECHRON) BUT I STILL SMELL STRONG FUEL ODOR,ANY IDEAS....

[@jorgezuni2818]

What if you don’t get check engine 💡 light and still get a bad smell when going over 60 mph on the highway or freeway 🛣 🛻 .. and it’s been going on for years ? Could it be of oil going to field stream in intake !

[@chrismckay8584]

That smell is carbon monoxide an you’ve been using it for years your exhaust is getting in one way or another I know a person who got a stroke cause of it

[@Livinlivin836]

Don’t know why this doesn’t have more views

[@alvkvy]

Can I get the link to buy the cats for a 2005 Lexus IS300, have both of those codes, plus P0153 P0133 P0174 and P0171, but I’m positive I got those codes from these two codes. And have every symptom you listed off.

[@1AAuto]

+Alexander Lara Trespalacios Thanks for checking us out! Can you please confirm which sensors you need replaced?

[@Scotty23]

So I have a Mitsubishi gallant with a v6 . It has a misfire. (Before the fix it gave a cylinder 6 misfire. And o2 bank 1 sensor 2 code.) I’ve replaced coil packs, spark plugs, and valve cover gaskets. After the fix for some reason it gave (injector circuit open for cylinders 2,4,&6 throttle pedal sensor, evap, and the same 02 sensor code from the first scanner). Can’t seem to find the misfire but a mechanic said maybe the cat is clogged up. He said unbolt the catalyst converter and start the car and see if the misfire goes away. Does trick sound about right ? For a diagnosis?

[@1AAuto]

+Markel Scott 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

[@Scotty23]

@@1AAuto thanks and I know . I was asking on my behalf to try ? Since I’ve tried everything else .

[@amadosugo]

Hey Master, the catalytic converter has solution? Can I just clean it? My mitsubishi eclipse need it but is too expensive.

[@murican1889]

The cleaning properties of a Kingston lighter fluid should do a perfect job of cleaning out the cat.

[@petermuniz9296]

Can you use hi flow

[@vegjeezy17]

I fixed po300 301 and 302. Now po420 comes on. Would a misfire cause the cat to go bad. What should I do

[@7PRINCE6]

That's the same question I have the same codes that you had the 300-304.. i replace the plugs now 420 is only one remaining on my 04 Civic it won't accelerate past 30 mph

[@andruwvasquez5830]

Can a clogged exhaust cause my truck to not start

[@hellohello8556]

Good video mate. 👍

[@gsjourney3054]

I know my oxygen sensor in my cat is faulty sometimes when reading honestly my cel goes away with premium shell gas I always get a smelly scent before it comes on though

[@erikarellanofelix1958]

Were are you located

[@river1403]

My 04 Chevy Blazer has clogged it's cat before. The previous owner ended up hollowing it out, and now I have a P0135 code. The O2 sensors pigtails have also been snipped. Thank goodness we don't have emissions testing where I live otherwise the truck would've been junk 😂

[@1AAuto]

+Sebas1509 Thanks for checking us out! 1aau.to/m/Shop-1AAuto-c

[@katherinechambers8131]

But its so expensive. My 2015 Hyundai Accent has a code for the converter. It runs great would bever know it had a issue. I've reset the code before it came back after a couple mths. The first time I used the Cataclean it worked service light went out. The second time it didnt . I don't drive much I stay local so I've been driving longer distance..didnt help light came on. I think I'm going to just keep an eye on it and if it acts different I'll have it checked out. I don't think I can ever afford a new converter.

[@fedreserv6133]

I have "Check Engine" lit, yet the car goes perfectly fine. Both oxygen sensors are changed and are working properly. Sometimes during the drive the light goes off itself, yet after a while, usually at lower RPMs and in 3rd or 4th gear, it comes back again. Also, when A/C is working and RPMs are low, light goes on. Any clue on this issue?!

[@moisesramirez387]

Same here did you figured it out?

[@willsrestorations]

You need to check your fuel trims with a scanner it seems as though your fuel trims are out of whack and you are perhaps pushing too much fuel and you are running rich which can destroy the catalyst converter and cause a lot of carbon inside the motor. Also change your PCV valve to make sure you're getting proper positive crankcase ventilation

[@cesarsandoval1699]

What about if I got leak and got a p0171 ?

[@usmanahmad-zp3xi]

Can we clean catalytic converter without removing it? Adding catalytic cleaner solution in fuel tank will clean it?

[@dannyr333]

Can a cat be worn also from lots of miles. My Elantra has 240k on it. My cat needs replacement it has all those symptoms. I just don't want the other variables : oil or gas or radiator fluid going in there cuz that could mean whole other issue plus the cat being compromised now.

[@lendavidhart9710]

I used to work with an old truck driver, and we were talking about our vehicles, while telling him about my truck, he interrupted me and said, time to jack up the radiator cap, and pull a new truck under it.

[@hippitymcstribbs4906]

Lmao! thats funny af thanks for this comedy break chief i needed that XD

[@soldier2gud4me]

Check engine light Ford focus 2008 model . P0037 - HO2S , Heater control circuit low, bank 1 sensor 2 P0136 - O2 sensor circuit, bank 1 sensor 2 P0030 - HO2S, Heater control circuit low, bank 1 sensor 1 Replaced the sensors still having the codes. Any help would be appreciated.

[@soldier2gud4me]

I cleared the codes and they returned after driving.

[@1AAuto]

+Smokingmonke91 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

[@Age_Of_The_GodJudah]

Currently have that code

[@keithcronk7980]

👍👍👍👍👍

[@alenmihelcic8267]

Must smell like egs! Injector, fire, holl on the pipe before cat sometime give error P0402

[@johnathanleonardo912]

My sentra had white smoke coming out and it was bucking and smelt like rotting eggs. My S10 is starting to smell like eggs

[@bugaloo67]

My mechanic replaced 5 catalytic converters and 5 O2 sensors and the check engine REFUSES to go off im done im gonna fist fight my mechanic soon I've been there 15 times and spent $1500

[@goodnightvids]

Remember there’s more than just that it could be the spark plugs, the throttle body any of the o2 sensor connectors or cables. All of that you can do it at home without any specific tool don’t spend money like rhat

[@VAcreeper]

Lacquer thinner

[@willsrestorations]

@LeonL47 it won't pass a state inspection because it will flash a code and turn the check engine light on which will make you feel automatically so please save your dysfunctional useless comments

[@jsc1235]

My 2019 f150 has a ruff acceleration.

[@tUrUrUmAnEtO]

If I have both codes ? 😅

[@zahimiibrahim3602]

Why do exhaust systems with bad cats have that rotten egg smell while older cars designed to run with no cat don't have the same smell?

[@Flunoir]

Will a clogged or broken catalytic converter prevent a car from starting? This is my current situation now.

[@1AAuto]

+FLUNOIR 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

[@oswaldocobian637]

No. Check your starter.

[@wooddee6079]

most likely you have a leak problem and if you dont you most likely have an 02 sensor problem. catalytic converters are meant to outlast vehicle

[@morthomer5804]

Is the egg smell coming from the driver or the car?

[@youngrenzy]

They stole mine so its straight pipe..... the shop wanted $1600 the repair 😂 I only paid $1200 for the car 😂 it runs fine but the check engine light will go off now

[@DanielPerez-oc8qs]

It happens on my car when use shell gasoline. Same smell. and notice my sister in law car do the same thing.

[@kellismith4329]

Swotch gas station

[@markallen4586]

The light I'm having problems with looks like an upsidedown headlight

[@fernandogianni2849]

Woow woow 😍💋 💝💖❤️

[@chelsealogan7037]

Really nice 👌 😍💋 💝💖❤️

[@1AAuto]

+Chelsea Logan Thanks for checking us out! 1aau.to/m/Shop-1AAuto-c