I disabled my rear O2 in the periphery bits today. I then drove the car far a while to see if the CEL would come back. It didn't but I got a new one it was for the EGR ( P0401). I then disabled that too in the periphery now there is no longer a CEL.

My question is: Does anyone think that the EGR code came up due to the disabling of the rear O2 or was it coincidence?