Help with P0420 bank 3 in a 2011 Buick Enclave So I literally bought this car today and 5 miles down the road the check engine light pops on. I get it checked and it’s P0420 bank 3 (catalytic converter not running efficiently).The dealership already agreed to help me out so I’m bringing it in on Monday but I did my own research too. I’m not car savvy at all but from what I’ve read it seems like P0420 could be caused by low oil and/or coolant. I checked and both the oil and the coolant are pretty low so I’m gonna grab some tomorrow, could that be what’s causing the problem code or is it more likely something bigger? Thanks in advance