Catless.. CEL?

[loonibab325i]

Can running catless cause a o2 sensor to send over a signal to turn on the CEL? I did the stomp test on my car and got 50 o2 sensor readings in a row telling me my o2 was bad... the o2 sensor has been in the car for seriously less then a couple hundred miles, it's pretty much brand new, car runs great though! ideas?

-Abe.

[dele30]

on obdII cars it will.

[OrganicMechanic]

I bet you connected grn/vio -fuel pump wires in adapter. back feeding the circuit. I posted the fix several times. fixed with a simple relay