Hello, I am having a devil of a time figuring out why my CEL stays on and I keep getting an O2 sensor code despite having twice replaced the sensor with OEM parts. I read online that this year C230 has a known problem with deteriorating wiring harnesses, due to an early faulty formulation of environmentally friendly plastic insulation. Has anyone had this problem, and did replaciing the wiring harness solve the problem?

 

i would check under the pasenger seat floor. I know on some of the older C classes the harness was there. I think the harness runs under the carpet and through the floorboard to the o2 sensor. the seat might have to come out. but pull up the carpet infront of the passenger seat and you should see a harness. no guarantees on this info.sorry. been a while since i worked on one of those.