Bad catalytic converter. What are my options


Been here awhile...
DubbuD, read your post #4 in this thread. You were wrong then. 'Fess up. The point was that IF it had been the cat, it would not have been covered by the 10/100,000 powertrain warranty.
Okay, but it isn't the cat, and I never said it was the cat? I asked if these issues should not be covered under the 10yr/100k mi. powertrain warranty. And they should. Still. It isn't a cat, and the motor should be covered. They sold him a cat, without properly diagnosing the vehicle imo. Quick cash grab for a shitty dealer, happens. I accept the warranties were different, and I do admit, that was something I was unaware of, since exhaust is technically part of the powertrain imo. It exhausts waste gas from the motor, which is part of the power train. Its seperate, Hyundai is weird, whatever, I'm over it. Didn't care to begin with, because I maintain; never was the cat my original point. That's something that was brought up because clearly someone missed my point.

My point is the dealer should be replacing motor parts under warranty since it is not a cat. Assuming the car was bought new in the US. A motor with water in the oil and misfires on half the cylinders or more should be checked for head and head gasket problems, as well as fuel injection issues, and spark/wiring problems. When someone comes in with a car misfiring, you don't just slap a new cat on it, charge the customer, and call it a day. You diagnose the issues. Its misfiring, and has water in the oil (that's a pretty hard thing to miss if you check the oil at all, which you should, the car is misfiring), and has thrown multiple codes related to emissions and mechanical failures. I'm saying none of this sounds like a cat. I've had cars with bad cats, really bad cats. This is my first new car in fact. Most of my cars until now have been old beaters. Never has a bad cat caused any of these issues on any of my vehicles. Is it possible? Very slim chance, but in theory. Definitely not the first thing I'd check/buy to try and remedy the issue.


Hasn't posted much yet...
Brigning this thread back from the dead...

I have a 2012 3.8 sedan with 105k miles(bought used and out of warranty) @ 62K. I had the same issue with a P0430 code that was intermittent at first but became more persistent over 6 months. Within a period of a week I was getting very bad performance, the exhaust tone had changed, I was hearing rattling from the exhaust, and cylinder 2 4 and 6 misfiring if I tried to push anything past 30% throttle. The primary cat on the driver side decided to give up and was crumbling, sending ceramic into the secondary cat and clogging it. I swapped the secondaries with test pipes and boom, car was running perfectly again. I'll need to replace the primaries at some point but for now its ok, aside from the occasional p0430 that needs to be reset.

Hope this helps someone!


Registered Member
Genesis Model Type
2G Genesis Sedan (2015-2016)
But, it isn't, and hasn't been, a cat problem...................... :confused:
Why are we still stuck on the cat? The motor, which is clearly broken and not running properly, should be covered under warranty. That's all I'm saying. Not the cat, the motor.

The thread is kinda inappropriately named tbh. Should be named "Engine Misfiring, Possible Bad Cat"

The bad catalyst code could be thrown for a number of reasons, since its just a sensor that is sensing the amount of emissions coming through the system. The code is literally just thrown whenever it senses something is wrong and the catalyst is not operating at what it perceives as optimal performance. Its the misfire codes which are most alarming, since those are actual, mechanical issues, and seem to be getting worse, not better. It is also likely that a leaking head, or the misfires caused the code to begin with, and then the other codes to show the problems were thrown after the general catalyst code. Since there does appear to be water in fresh oil, that to me screams bad head or head gasket, which could lead to a P0430 Code, and also lead to misfires.

Its a motor problem, it should be covered. It is NOT a catalytic converter problem causing all of these symptoms.
So did you ever figure out the problem? Sounds like my 2015 5.0 minus the water in the engine and I'm getting desperate to know what is wrong after swapping out my engine and fuel pumps and everything else the dealer thought they could sell me!! Also did yours shift funny when you put the peddle on the boards?