So I noticed last week I took my car to the dealer for the nox sensor recall, dropped it off. They called back and said they had to order the part so I picked the car up and was fine till the other day I noticed the heater wasn't working looked like due to lack of coolant, so yesterday I topped it off and ran it for a good bit and it sucked it down some till it seemed like it was good, there's no coolant mixed with oil, the seal seems to be good and there is no leak or puddle on the ground any where??? Ok so today I took it to get the nox sensor recall done today. Picked it up and noticed it said sensor install and ecm reprogrammed. Figured ok it's a sensor.. so I pulled into my lot and check under the hood and seen I lost a good bit of coolant again? Wth?? So my question is does doing something or replace the sensor have something to do with coolant just disappearing??? Idk what to do other then keep checking it and topping it off hoping that it stops randomly vanishing...