i added on a straight pipe and it threw a cel. it read a P0420 code which is "Catalyst System Efficiency Below Threshold". After I installed the o2sim, two new codes came on :

P0132 "Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Circuit High Voltage"

and

P0141 "Secondary Heated Oxygen Sensor (Secondary HO2S) (Sensor 2) Heater Circuit Malfunction"

When i deleted them, but one remains which is the P0141. Does anyone know what might be the problem?