California Catalytic converters?

[EAD15]

Most of those problems that you have dealt with sound like they are related to the overheating. What was the cause the overheating the first time? If you over heated twice, do you have any kind of coolant or oil consumption? Odds are one of those two things are what killed the cat, plus California cats are really expensive. Honestly, I'm not sure what answer you are looking for here. I think there is a wagner California approved cat for in the $600 range for the earlier car. What are the laws in California about used cats, the sonic and cruze 1.8 both should use the same, so you might be able to get one from a yard.

What codes do you have? if it wasn't for the smell you described, I think a lot of use have replace one or both of the o2 sensors. I have done both, either will cause drivability issues somewhat, but the cat was ok in my case.

Petrified, used cats are a no-go in California. No yard could (legally) sell a used cat. It's brand new or nothing. Any aftermarket intake/exhaust parts need California Air Resources Board (CARB) approval. Aftermarket cat without a CARB stamp, instant fail.

[06T200]

The California cat cartel is rough on the wallet. I'm not aware of any CARB approved for 2010 in the aftermarket yet.