Q: My catalytic converter is rattling and there is smoke coming from my car. Is the catalytic converter faulty?

asked by on

My catalytic had rattling for some time. I just never looked into it(BAD IDEA). Then 3 weeks ago I started my car, and it was idling so BAD. as if no air or pressure was being released through the muffler. I took it around the block and the car wouldn't even accelerate! NO back pressure. Then after I stopped the car SMOKE started coming out from the bottom. NOT from the engine or anything close to it. I took it to my mechanic for troubleshooting. I thought it might have been an ignition problem or battery etc.. he found nothing wrong with the coils or spark plugs or battery or anything! Heck he even checked the timing chain! the device just kept saying "RANDOM MISFIRE". NOTHING specific. Then i mentioned about the smoke and cats so he said that might be the problem. HE advised to take it to a cats/muffler shop. Before i go, i need a second opinion. It would be of great help if someone gave me a good explanation of what the problem might be. Thanks guys.

Kind regards, Kevin

My car has 150000 miles.
My car has a manual transmission.

It is possible the catalytic converter got hot enough to fail on the last trip you took before this started. No pressure from the exhaust is a good sign that the car can’t breath. This may be because it cannot get enough air or because it cannot exhale.

The only way to confirm definitively is to perform all of the tests the previous mechanic performed to confirm the diagnosis. There are a few other sensors that may cause similar issues, but the scan for diagnostic troubleshooting codes would have alerted you at that point. A muffler shop will be able to confirm if the cat is bad. You can knock on it and see if you hear a rattle of some sort. This is a sign the filter inside has become heated, brittle, and broken off on the inside.

I recommend having a certified mechanic, such as one from YourMechanic, come to you to determine if the catalytic converter needs to be replaced and why smoke is coming from the car.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My catalytic converter is rattling and there is smoke coming from my car. Is the catalytic converter faulty?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I have a leak in the coolant system that I have narrowed to I believe is the water inlet tube off of the lower radiator hose.

First off, I would say it would be best to pressure test the cooling system to verify where the coolant is coming from. With the complexity of repairs to the cooling system on this vehicle, it may be worth the...

Q: Positive long term fuel trim.

The fuel trim numbers mean that the fuel is leaned out. If the number is at 0, then there is no change. If the numbers go to a positive increase, then the fuel system is leaning out. If the numbers...

Q: Is it possible to remove Bracket bolts without removing caliper pins?

The complete bracket and caliper can be removed this way. I have seen this many times where the caliper retainer slide bolt seizes. The reason is no one lubed the slides and pins when they did the brakes in the...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...