Just wanted to keep everyone posted on this, if you go to the dealer and get a replacement block heater cord....(DONT). The new cords have a temp. sensor in them and they will not let power go to the block heater unless the temp is 0 degrees or lower. Just as an FYI.... i asked the service manager why and he said that some of the block heaters where throwing a check engine light because of a false reading from the fuel temp sensor. Anyone ever heard of this??? I tried to get the old style plug but no dice....... i think i will be cutting the end of this cord off with the sensor and replace it with a regular style plug!!!

It's funny... My '08 owners manual says I should have the temp sensor cord that will not turn the heater on above 0*, but I have a regular cord

I had the code come up and was read the riot act by the stealer but I have found that if I plug the heater in while the engine is still warm I do not throw codes. I have been able to plug in at temps in the 20s this way.

Thanks for the info. My block heater and cord have to be replaced now. It just smoked itself when I plugged it tonight. Good thing I was still messing around outside. I looked like someone was welding under my hod, a bunch of sparks and bad crack, hissing and popping sounds. I started to pull the cord out and then said screw it, I can let the dealership do it. It had made some noise a few times before this happened but I thought it was normal, OH WELL. I wounder if I can get a old cord???? The plug on the heater itself is cooked. One pin is still in the cord side when I pulled it apart. I'll figure something out I guess, maybe wire my own cord on the new heater?????

Well if it is a round plug that has two pins in it you can go to any Freightliner dealership or Kenworth Peterbilt exc. and ask for a heater replacement cord, but im not sure what the end looks like....... if any one knows please respond....

Mine has 3 pins at the heater. One is still in the cord side. too busy at work to figure anything out today. I got thursday off so I will go to the dealership i used to work at figure it out.

Well there is a somewhat easy fix for the new cord. Go to home depot or Lowes and get a new male end. Just cut the end off the new cord and put the new one on, the thermostat is located in the block heater cord near the end.....

Someone on this forum told me to ask the dealer to do the ECM updates to suppress these false codes. It had happened to me the first time I plugged in to test the block heater. I've had no problems since and have often plugged in when it's not very cold out. I declined the updated cord and am glad I did. I also picked up a cheap code reader so I can clear them myself if it does happen again.
...Fred

So you can get a choice on the cord????????????????