Chevy equinox 2013 changed the y pipe because of leak in the aft part of the flex coupling. Also removed the aft converter because I replaced the transfer case. Had no codes prior to working on the car. After all the work code 430 popped up low efficiency on number 2 bank. Found a small leak at the flange of the converter to y pipe. Fixed, code would not clear. Changed O2 sensor lower on bank two y pipe. Code still will not clear. Check engine lite comes on after driving about 20 miles.
thanks for the help.
steve

 

Check the wiring to the 02 sensor as it could have been damaged during all the work you did. You stated that you removed the aft converter. Did you replace it?

 

I did look at the connector looked okay. No I didn’t change the converter. Installed new gasket at the manifold.