Ok I had wires, plugs, pcv, egr valve and header gaskets replaced and after doing so Im now getting an SES with a code 154(oxygen sensor circuit no activity detected-pre convertor sensor, right bank). Well I just replaced my o2s in january and they were fine until I had this work done?? Does anyone have any clues on what would cause this code and do o2s just die out after a couple of months? Please help me!

Rich T