P1133 GMC -2001 5.3 replaced all plugs and wires, and all 02 sensors and now getting this code

Question

I changed all 02 sensors, replaced spark plugs and wires, and map sensor. Was on my way to get oil and cleaners and this code came on. Reset code all ok went back to closed loop then it came on again 2 hrs later. But as long as I reset code it runs normal open loop goes back to closed loop

Answer 1

Open loop, the loop status has to be closed. in order for P1133 to set. If this code is setting irregardless of the loop status then you have a open circuit to the 02 sensor heater circuit. Either the harness of the 02 sensor itself