yup, crack pipe. If you have not changed the sensor, I definately would. It's a cheap part that is a pain to get at. You can get the complete thermostat housing kit that has the o rings and new plugs and everything from GAP for less than 150, depending if you get the plastic pipe, or the metal. I just did this about a month ago. I replaced everything, and went with the metal pipe because it is a pain to do and I did not want to do it again. The housings are known to fail, that is why there is the kit. Easier to do it all at once.