I've had this chevy for a year now and I never fixed this issue it had (simply because I got this car for the biggest steal) so I always just let it exist. The issue occurs after starting I can't leave the car unattended because if left not revved for 30 seconds it will begin to run choppy then die. If I sit and give the throttle a few small taps to keep rpm up after 30 seconds - 60 seconds the problem no longer occurs and the car runs and drives no issues. It happens no matter the weather it's only the first 30-60 seconds it runs the risk of dying then as soon as it gets some gas/revs for a min it runs great. I have a picture of the code it gave it reads P0420 Catalyst System Efficiency below threshold bank 1. Any help? and does it sound expensive?

Thanks

 

Chevybro what year is your vehicle.. I am having the same issues that you are having on my 2012 equinox

 

I have a 2013 with similar problem. If I drive before rpm drops below 1000 after startup the engine will stall briefly then run perfectly thereafter. When I wait until rpm is less than 1000 it never stalls. It acts like it leans out during the warmup process. No codes are set.

 

im getting a code with mine P0420 Catalyst System Efficiency below threshold bank 1. and sometimes i get a code for bank 1 sensor 2 running to rich. i just wish someone could help us guy out.

 

I finally solved this problem by changing the forward oxygen sensor for the correct one. The previous owner's repair shop had installed a wrong oxygen sensor that did not warmup quickly enough resulting in the computer leaning out the engine. With the correct oxygen sensor warmup is as you would expect it to be.