eli5 If my catalytic converter is slightly hit, how would it affect the performance of the car?


Like my car vibrates after 120km/hr. That really shouldn’t be happening. Let alone from a hit Catalytic converter.

In: 2

It probably isn’t the catalytic converter.

Check the tires (simple things first – pressure correct, not worn down excessively on one side etc)

Next get the wheels balanced and aligned. They should check the joints too.

Next culprit is the brakes and suspension. Things broken or worn shocks etc.

Next probably would be engine mounts. (they get hard or wear out)

Next would be to check the drivetrain – differentials, driveshafts etc

So the first stop would be a tire shop and if that doesn’t work a mechanic.

You may be feeling the exhaust system (which the catalytic converter is a part) rattling if the impact broke a weld or damaged a clamp. Odd that it wouldn’t start vibrating until you reached a certain speed, but it happens – some sort of harmonic resonance thing going on. If you can get under the car, check all the clamps and welds and see if you can shake the exhaust piping with your hands (obviously do this when the car is cold). If everything seems tight, then that’s probably not what’s causing the vibration.

Check tires first – even brand new (or newly mounted) tires can have issues – defects, out of balance, etc. And whatever hit the catalytic converter might have damaged a tire too.

Alignment is next. If the car stays straight when you remove your hands from the wheel, the alignment s probably ok, but that’s not a definitive test, especially if the issue is in the rear.

If these two things don’t solve the problem, then you need to bring it to a good mechanic to evaluate – there could be lots of causes, and you want someone you trust who is experienced and knowledgeable to assess.

Good luck.