I have a stock 2005 F250 6.0 Super duty and recently had the check engine light come on, after plugging my scanner in I saw code PO672 so I replaced all the glow plugs on the drivers side (#'s 2,4,6,8) along with the harness since I could not remove it without damaging it. After replacing the glow plugs and harness I cleared the code thinking problem fixed but almost immediately the check engine light came back on. I've checked the connections on the harness and the plugs on the glow plug controller but this code keeps coming back. My registration is due today and I need to smog my truck this year and it will not pass with this light on and to top it off after checking the monitors prior to do the smog check on my scanner the EGR is not resetting or being recognized as being on the truck is that makes sense. I took the EGR valve out and cleaned it to see it that will help but after just driving my truck this morning to work the EGR has not completed the cycle and not sure if it will. My smog guy said it possible that the code with the glow plugs is stopping the EGR from cycling completely. I'm not mechanic by any means but I'm not afraid to get my hands dirty and work on my own truck but I am not having much luck with this issue so if anyone has had this issue or has some advise it would be greatly appreciated!