Hopefully someone can shed some light into what's going on. For the last couple of days we have been in a cold snap around -30C. I was driving the car and noticed that the ambient (outdoor) temperature sensor would read the proper temperature upon starting the car but, after driving for 15-20 minutes it would shoot up to +10-15C.

I took a look around the engine bay, and there is no visible signs of coolant leaks (even tho I know the temp sensor is behind the front bumper and has nothing to do with the engine temp). I noticed whenever I run the fan on the heat cycle (fresh outdoor) it would blast hot air which would almost burn my hand.

Whenever driving, the temperature sensor (the outdoor one not the engine temp sensor) would rise upon acceleration but whenever idle it would go back down.

I should say the dash does not light up with any of the warning lights. Turned the engine off, inspected the coolant after removing the radiator cap, and there is a bit of bubbles.. The overflow coolant container is in between full and low. I'm thinking the thermostat maybe stuck closed.. Anyone have any other suggestions what I should check. Does the outdoor ambient temperature even have anything to do with the HVAC/Engine temp?

information about the car..

2014 cx-5 2.5Gas 120,000 KM cooling system was inspected (pressure tested by mazda last year and no issues)

  • Why do you suspect overheating? The outdoor temp sensor reads the outside temperature not the engine coolant temperature. Perhaps the sensor is just bad.
    – jwh20
    Commented Jan 20, 2020 at 12:26
  • Welcome to Motor Vehicle Maintenance & Repair! Commented Jan 20, 2020 at 14:14

1 Answer 1


As jwh20 stated in comments, the ambient air temp sensor is for the outside and has absolutely nothing to do with the engine coolant. From your description, you've not indicated anything which shows the vehicle is overheating. Your description leads me to believe you are worrying about something which doesn't exist. The vehicle is most likely running as designed with absolutely nothing to worry about.

  • I was more concerned about the indoor cabin temperature being extremely hot. I wasn't sure if this was being pulled in from the engine compartment and only figured the outdoor temp sensor was more of a aesthetic dash component which had nothing to do with the hvac of the car
    – ottguy
    Commented Jan 20, 2020 at 15:04
  • 1
    If you are feeling as though the hvac is putting out hot air, it probably has more to do with it being so cold outside, you getting cold, then feeling the heat of the vents feels hotter than it should be. Seriously, I truly doubt you have a thing to worry about here. Commented Jan 20, 2020 at 15:22

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .