What’s up my dudes, I’m new here I have a 2013 g37xs with 155k and today the “service engine soon” light came on dash and I scanned my car and got the P0430 catalyst system efficiency below threshold bank 2 code. I know this probably has to do with the 02 sensor or cats but I don’t really know what to do to diag this. I know my cats are pretty much shot I’ve had a ticking coming from the exhaust from some time now and it’s coming from my cats. Also my exhaust is pretty shot too I’ve had an exhaust leak due to rust but after the cats. I just want to know what you guys think I should do first, should I go ahead and replace my 02 sensors and then go from there?

 

See if you can get the readings off the O2 sensor after the cat. The reading shouldn't move much. If it's all over the place, it's a good chance it's the sensor.

 

How about you fix all of your exhaust leaks first.