PID 46°C
Ambient air temperature
Outside air temperature as the car's own sensor measures it. The unit uses it to work out air density and to run the climate control. Do not confuse it with intake air temperature (PID 0F): that one is almost always higher because it is measured under the bonnet, next to a hot engine. If the ambient reading is stuck or plainly wrong, the climate control starts behaving oddly.
What is normal
Check it against the weather. A few degrees off on a warm car is normal; ten degrees off is the sensor.
These figures hold for most cars, but the maker has the last word: some engines run hotter or idle higher by design.
We have a detailed piece on thisIntake air temp sensor: P0111, P0112, P0113 and fuel use
How it feels behind the wheel
The same fault shows itself in different ways. Each sign below says what to look at in the live data.
The temperature gauge is climbingThe needle goes above its usual place, there is a hot smell from under the bonnet, and the heater may blow cold on a hot engine.The heater blows coldThe engine is warm but the heater blows cool or barely warm air. Sometimes one side is warmer than the other; sometimes it only gets warm while driving.The air conditioning will not come onThe button presses, the light comes on, but there is no cold air. Sometimes the compressor clutch does not click when switched on; sometimes the cold disappears only in heat or in traffic.Slow to warm up, the heater blows coldThe temperature needle sits low for ages, the cabin stays cold, and on the motorway it gets worse. Consumption rises noticeably.The cooling fan runs all the timeThe fan roars right after starting and does not stop even on a cold engine or in frost.
How to see it
In CarScan: the Live data tab, «Start polling». The app asks the car several times per second, draws a graph and remembers the highest and lowest value of the trip.