Top 10 Symptoms of Bad Catalytic Converter
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- Опубліковано 6 лют 2025
- #catalyticconverter
What is a Catalytic Converter?
A catalytic converter is an important part of the vehicle’s emissions system. A catalytic converter is a mechanical unit that converts toxic gases emitted from the IC engine into less-toxic pollutants by catalyzing a redox reaction. It is designed to extend the life of the vehicle but can fail if it becomes clogged.
Symptoms of Bad Catalytic Converter
1) Check engine light illumination
2) Poor Engine Performance
3) Black smoke from the exhaust pipe
4) Engine Misfires
5) Failed Emission Test
6) High or Low Fuel Consumption
7) Rattling Noise
8) Smell of Sulfur
9) Discolored Housing
10) Starting Issues
Disclaimer:
This video is just for educational purposes only. We are not in the auto repair business nor publish automotive service manuals. This video is not reviewed or authorized by any vehicle manufacturer. This video is intended only as general guidance. Every system is slightly different, so refer to the owner’s manual of your vehicle for any specific information about your model. Remember that only proper service and repair procedures will ensure your car's safe and reliable operation.
Copyright Disclaimer:
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my car s catalytic converter we as stolen at a garage and soon as it was gone my car s performance decreased n indeed all what you just highlited is very true
If you don’t want to run off of a cat converter look into carbon air intakes, it completely removes the cat converter and makes pure exhaust from the engine to the pipe
How does that work
Do you have to take the cat off or air punt
@@Aj-hc9zf I got my cat off but I have a modification that’s basically straight exhaust from front to back, improves airflow tenfold, it’s legal anywhere in the States, sounds badass, and doesn’t expose me to toxic exhaust, it’s a plus all around especially on a VTEC
@@Aj-hc9zf so like I said it replaces the cat converter and makes straight pipe from front to back, it’s essentially is better airflow and less weight
@@CT-5689so it’s a straight pipe my car is running a bit ruff took to mechanic they said need to replace it but if I could just straight pipe it’ll. Be cheaper
I call Bs on the converters, cars can be tuned to have equal to or better output as a converter, However, the additives being mix in gas cause a concern, Gasoline of today is no where near as clean as it was 30yrs ago.
Can a bad catalytic converter cause white smoke when I start the vehicle? Engine starts, a lot of white smoke and water from the exhaust which eventually goes away after a minute or two
Also have same problem ..do you solve your problem??
A bad catalytic converter typically doesn't directly cause white smoke when you start a vehicle. White smoke upon startup is often a sign of coolant leaking into the combustion chamber or exhaust system. This could be due to a variety of issues such as a blown head gasket, cracked cylinder head, or a damaged intake manifold gasket.
However, if the catalytic converter is severely clogged or malfunctioning, it can cause excessive heat buildup in the exhaust system, potentially leading to other problems such as overheating of the engine or damage to other components.
@@YounisMengal-vlogs I opened my intake/exhaust manifold and found a lot of oil inside. It was horrible. The engine needs to be disassembled
I use Benz e350 w211, could it be the reason ,it jerks on high speed and reduce speed until it stops responding to acceleration, but resume normally after cooling off, yes I just changed the 12plugs too
Thanks for the helpful tips I think my car is doing that already for awhile I appreciate it
@@abramcortes-meza5134 Thanks for watching and appreciating
Very helpful - thank you for making this video.
My mustang made rattling noises out of nowhere with me cruising like 45 and hasn’t stopped also check engine light came and the 02 sensor code came up and failed emissions is that catalyst failure ?
It's possible that the rattling noise and the check engine light indicating an O2 sensor code are related, but it doesn't necessarily mean it's a catalyst failure. Rattling noises could be caused by various issues such as loose parts, exhaust system problems, or engine issues.
The O2 sensor code could indicate a problem with the oxygen sensor itself, or it could be a symptom of another issue affecting the air-fuel mixture or exhaust system. A failing catalyst can sometimes trigger O2 sensor codes, but it's not the only possibility.
@@MechanicalBoostso I got no rattling noises on my 95 mustang, but my performance has been down dramatically, on the first cold start it acts like it wants to shut off until I idle it for a bit, I smelled fireworks or rotten ends coming from somewhere (not the hood thankfully) tonight could that be the cats?
@KingKhiddoxYuneek
Yes, the symptoms you're describing could point to a failing catalytic converter (cats). Here's why:
1) Performance Drop:
A clogged catalytic converter can restrict exhaust flow, which in turn reduces engine performance. This could explain the dramatic drop you're noticing.
2) Cold Start Issues:
A restricted or failing catalytic converter can cause a rough idle or even stall-like behavior until the engine warms up, as it struggles to maintain proper airflow and fuel ratios.
3) Rotten Egg or Fireworks Smell:
That smell is likely hydrogen sulfide, a byproduct of incomplete combustion caused by a failing catalytic converter. If it's more "fireworks-like," it could also indicate an issue with unburnt fuel in the exhaust system, which could overheat the cats and damage them.
I have 6. It’s a loud rattling noise almost reminds me of metal pot lids rattling together.
Inspect your catalytic converter and change it
Mine too! I have had it for awhile I thought it was my fog light rattling around in its housing. Now my car is loud like a roar almost. Guess I'll get them changed
@@gameova77 it’s expensive 😭
The morning I drove to work, my car ran fine. I needed gas so I put 93 in my car and arrived to work. I started my car that night leaving from work. The car felt normal until 10 min into my drive, the turbo felt jerky, 10 more minutes into the drive I was idling at a red light and smelled a car that has no cats, I have cats so I assumed it wasn’t me, once I got off the red light all I hear is my car rattling and popping my car naturally has a pop tune so all I hear is my car popping, like it had antilag, and I saw grey/dark smoke coming from my exhaust. I couldn’t go beyond 3k rpm. Would my catalytic converter be the culprit?
@@RamzaBeo Based on the symptoms you described, it’s possible that your catalytic converter is involved, but it may not be the sole issue. Let’s analyze the situation:
1) Jerky Turbo and Reduced Performance:
This could indicate a restriction in exhaust flow, potentially caused by a clogged or failing catalytic converter.
Alternatively, it might point to a misfire or an issue with the air-fuel mixture (like fuel contamination or injector problems).
2) Smell of Unburned Fuel/No Cats:
If your catalytic converter is failing or clogged, it might not be processing the exhaust gases properly, leading to a strong smell.
This can also be a symptom of incomplete combustion due to misfiring or an overly rich mixture.
3) Rattling and Popping:
The rattling could indicate a broken component inside the catalytic converter, such as the ceramic substrate.
The excessive popping could result from unburned fuel igniting in the exhaust, which might happen due to improper combustion or a failing turbocharger.
4) Smoke (Grey/Dark):
Dark smoke suggests incomplete combustion, which could be caused by a failing turbo, a rich air-fuel mixture, or fuel contamination.
If the turbo is compromised, it could be leaking oil, which also produces smoke.
Catalytic converter, fuel quality, turbocharger and ignition system are the key culprits.
While the catalytic converter is a strong suspect, a full diagnostic will confirm whether it’s the primary issue or if other systems are involved. If possible, avoid driving the car until the problem is addressed to prevent further damage.
@ the only codes that came up where misfires on cylinder 1 and 3. During that night the CEL came on then went off. Then it came on and started flashing. And btw the car is undriveable, the car feels like it’s suffocating when I press on the gas. The only way I was able to get home that night was just allowing the engine to coast me to my house. My turbo never made any whining sounds prior. Plus this is a new turbo. It’s a stuffed K03(golf R) turbo. I also put gas in my car that day too before work. It could also be bad gas too?
Hello i have a 2004 nissan titan would a bad oil filter make the vehicle not start btw im gonna get a new oil filter soon and im gonna get a catalytic converter and try and get a manifold too
A bad oil filter itself typically wouldn't prevent a vehicle from starting. The primary function of an oil filter is to remove contaminants from the engine oil to keep it clean and protect the engine. While a severely clogged or damaged oil filter could potentially restrict oil flow and lead to engine damage over time, it wouldn't directly cause the vehicle not to start.
Can a melted catalytic converter to give a missfire?I have a mazda 2.0 petrol engine with Missfire on cylinder 4 (P0304).I changed spark plugs, ignition coils, injector, O2 sensor but still have the error.Also i have checked compression, fuel pressure..both are good.
Please help me😢
@@BrunoBMS Yes, a melted catalytic converter can cause engine misfires. When a catalytic converter melts, it often becomes partially or fully blocked, restricting the exhaust flow. This creates excessive backpressure in the exhaust system, which disrupts the engine’s ability to expel exhaust gases efficiently. Here’s how it leads to misfires:
Reduced Exhaust Flow: Excessive backpressure affects the air-fuel mixture in the combustion chamber. When exhaust gases can't exit properly, they can interfere with the fresh intake air, leading to an inefficient combustion cycle.
Overheating: Blocked converters can increase exhaust gas temperature, causing the engine to run hotter. This can damage components, including spark plugs and ignition coils, leading to misfires.
Oxygen Sensor Issues: A malfunctioning catalytic converter can also affect downstream oxygen sensors, which measure exhaust gas composition. This can cause incorrect adjustments to the air-fuel mixture by the engine control module, leading to poor combustion and misfires.
@@MechanicalBoost thanks a lot, i really appreciate your explanation 🙏.That makes sense, because i forgot to tell you that the engine is overheating, and i changed the O2 sensor, the spark plugs and one ignition coil because was demaged.Anyway..i have one more question:assuming that my catalytic converter is melted, why this missfire is only on the 4th cylinder all the time?
@@BrunoBMS
When misfires consistently happen in a specific cylinder, like cylinder 4, it could be due to a few reasons:
Exhaust Flow Dynamics: The layout of the exhaust manifold or the catalytic converter might cause cylinder 4 to be more sensitive to any restrictions or back pressure, making it more prone to misfire when airflow is blocked.
Heat Buildup: If cylinder 4 is farther away from the cooling system's main flow, it might be more prone to overheating under increased back pressure, leading to a higher likelihood of misfire.
Fuel/Air Mixture Distribution: In some engines, certain cylinders (like cylinder 4) may receive a different fuel/air mixture than others, especially under conditions where exhaust back pressure is affecting overall engine performance.
Pre-existing Weakness: If cylinder 4 has a spark plug, coil, or fuel injector that is slightly worn or weak, the additional stress from the back pressure might be enough to push it into consistent misfire territory.
If you’re experiencing repeated misfires in cylinder 4 with a melted catalytic converter, it’s a good idea to inspect not only the exhaust system but also the ignition and fuel systems in that cylinder to rule out any additional issues.
@@MechanicalBoost Can the catalyst be melted if the nox test comes out ok?
Does bad cat make rattling sound(just like an engine without engine oil sound) cause i was in montreal and my car made very weird rattling noises just like i mentioned before whenever i go uphill or start moving after a stop the rattling sound was there and also sometimes my low engine fuel light comes on sometimes but next day when i went to my car mechanic he said oil level is normal and the car is not burning any engine oil.
Yes, a bad catalytic converter can sometimes make a rattling sound, similar to the sound of an engine lacking oil. This typically occurs when the internal components of the catalytic converter become damaged or loose. The rattling noise may be more pronounced during acceleration or when the vehicle is idling.
@@MechanicalBoost hey i really appreciate the reply but i have another question adding to my first one that so whenever that sound comes sometimes the low engine oil symbol also lit up for 1 sec not ever-time but lets say 5 out of 2 times but my car’s engine oil level (was-is) normal and it is also not burning any oil
Im having this issue with my 2017 Chevy Sonic @MechanicalBoost
I have only four out of the 10 symptoms, 2016 nissan frontier, it doesnt go fast like it did, sluggish exceleration, high fuel consumption, thats the main things . About two years ago i smelled sulfur for a while and i saw smoke come out tail a few times,. I may have smelled sulfer only a few times the past year. I took it in for a battery in 2023 when this started and they told me i need my fuel injection service and replaced spark plugs. I hope its not the CC thats a 2,000$ part. But im worried is the sulfur smell mean its only the CC. Thankyou.... I goggled what else can smell like sulfur, it said CC, Fuel filter, fuel pressure sensor. So I'm thinking it's the fuel injection, like the man said at viking automotive.
Yeah cc can have a bad smell im getting mine fixed now. Hopefully that’s the issue im getting sparks coils done too
Would a broken catalytic converter cause a car to stop all acceleration responses and i am having tontake my foot off the pedal and downshift then the power kicks back in hard and then goos good again but randomly do it over again (think my catalytic is damaged because my exhaust is rattling at low rpms and at idle itbget a random exhaust rattle
A broken catalytic converter could potentially cause issues with acceleration, but it wouldn't necessarily stop all acceleration responses on its own.
@@MechanicalBoostI have the same problem. 1st & 2nd gear struggle but everything goes back to normal the more I drive.
@@bobbystereo936 If your car struggles in 1st and 2nd gear but runs smoothly as you drive more, there could be several potential causes: such as
Transmission Fluid Issues: Low or dirty transmission fluid can cause shifting problems, especially when the car is cold. As the car warms up, the fluid becomes more effective, which might explain why the problem diminishes.
Clutch Problems (Manual Transmission): If your car has a manual transmission, the clutch might be slipping or not engaging properly in the lower gears. This can be due to wear and tear or issues with the clutch hydraulic system.
Transmission Control Module (Automatic Transmission): The transmission control module might have issues, causing improper shifting in lower gears. As the car warms up, the module might function better.
Engine Performance Issues: Problems with engine performance, such as issues with the fuel system, ignition system, or air intake, can cause poor performance in lower gears.
Vacuum Leaks: Vacuum leaks can cause erratic behavior in the engine and transmission, particularly when the engine is cold.
Cold Engine: When the engine is cold, it might not run as smoothly as when it warms up. This can affect the performance of the car in lower gears.
Transmission Wear and Tear: General wear and tear of the transmission components can cause issues in the lower gears. As the car warms up, the parts might expand slightly and function better.
@@MechanicalBoost Funny you mention that! I recently had the water pump fixed & It looked like antifreeze was leaking outta that transmission box or gear box or whatever that is?
My car was doing that and the mechanics changed the spark plugs and coil packs it's a for now patch job until the cat. Converter can be fixed or I can give up the car runs better. Continue to out fuel injection cleaner and catalytic converter cleaner in gas tank with 16 gallons of gas and it kicks out bad orders if you have bad orders
I have a 2004 Honda Pilot, can a bad catalytic converter cause it it to start?
A bad catalytic converter typically wouldn't cause a car to fail to start on its own. However, a severely clogged catalytic converter could potentially contribute to engine performance issues that might indirectly affect starting.
TQVM!
I just bo anew catalytic c but my car still show check engine light.
What can l do
You should contact a professional mechanic for deep inspection or do it yourself. Your car may trigger check engine light due to different reasons such as a bad spark plug, bad ignition coils, bad fuel injectors, engine misfire, and many more. Therefore, you need to properly diagnose the issue.
@@MechanicalBoost l took to the mechanic and checked the error code was still p0420... Catalytic converter below threshold on bank 1... Something like that
I bought anew catalytic converter and still showed same problem. Am confused cause the more l visit the repair shop the more money I spend and no change.
@@sulaamisi You should also check your oxygen sensors because they may also affect the performance of your catalytic converter and trigger the P0420 code. Also check your system for Exhaust Leaks and test the ECM. Sometimes a bad ECM may also inacuurately trigger this trouble code.
Problems with fuel injectors, fuel pressure, or a malfunctioning fuel mixture sensor can cause an imbalance in the air-fuel ratio, which can affect the performance of the catalytic converter.
@@MechanicalBoost alright thanks for the advice. I try them out
Usually never goes bad, however they do sometimes. Family member had a Chevy Blazer having engine problems, had check engine light,
Had over 120,000 miles
Called me I said it might be plugs, spark , or anything 🤔
Took it straight to mechanic shop used that high tech computer mechanic, cost 3500 dollars
2 weeks later started acting up again , again called me I went there and tested the fuel pressure, spark plugs ,
Funny but when you gave it gas the fuel pump pressure fell down terrible and it would miss,
Installed a 250.00 fuel pump never had no more issues,
They do go bad but check everything else never trust that computer shit !
My engine light went on over a year ago and I did'nt want to deal with it then . I was out of town and it happen in parking lot went to start Vechile and it startrd and it turned off it would turn over and then just turn off..... I regret it now stupid move cost me $500 dollars to have it towed back home.
Therefore, it is always recommended to contact a professional mechanic as your vehicle starts to produce even minor problems... If you ignore minor issues, they may become bigger over time and cause costly repair.
My car only have the check engine on
Thanks for giving me a reason to go catless
Can it destroy the engine
No, usually it can't destroy your engine but it may badly affect your car's emissions
@@MechanicalBoost I'm driving a car with a bad cat , if I change it will it be ok or have I damaged the engine now that it will fail in emissions?
@@timothyorourke7116Driving with a bad catalytic converter (cat) can cause some issues, but it depends on how long you’ve been driving with it and the overall condition of the car.
1) Emissions: A faulty catalytic converter won’t process exhaust gases efficiently, so your car is more likely to fail an emissions test.
2) Engine Damage: If the catalytic converter is clogged or restricted, it can cause a buildup of backpressure in the exhaust system, which might lead to overheating or other engine performance issues. Long-term driving with excessive backpressure could harm the engine.
👍👍👍
Po302 ???
Explain your question
This guy is just naming anything and everything
@@jh.1528 no I just explain the common symptoms that are usually found due to bad converter
Stoooooid robot voice