Anyone else notice how "slow to react" ambient air temp readout is?

[paris1]

I've noticed that my dash temp readout is hardly ever consistent with those of banks and other public temp displays I pass in town. Always seems like it 5 or even 10 degrees higher or lower and usually it feels like the dashboard reading is the one that's innacurate. From my observations, it appears that the CX-5 retains the last reading taken before it was parked and is very slow to react when the engine is restarted even though it may be several hours later and the outside air temp might have changed by + or - 15 degrees. I'm wondering if the placement of the sensor behind the front bumper keeps it insulated from changing temps and that's why it takes so long to catch up with reality. Not a big deal, but a minor irritation and I'm wondering if anyone else has noticed this?

 

[TreyP]

What I have noticed is that it is affected by air currents, which is different than any other vehicle I have owned. For example, the other day I came out of work and the gauge read 102*, but within a few yards of driving the temp was falling quickly enough to watch - 101* 100* 99*...until it evened out at 89* within a mile or so. I was in direct sunlight both while parked and while driving. A good temp gauge would not be affected by the air currents.

 

[paris1]

That's very different from mine. Example: this morning I went to a farm market about 25 miles south. Parked it in the shade for a couple of hours and when I started it up it read 69 degrees while a nearby street readout read 80, which everyone in the car agreed felt closer to the truth. Took about 15 minutes and 15 miles of freeway driving for the car's readout to creep up to 76 degrees which, going north in my area, was probably reasonably accurate.

 

[MikeM.]

From my observations, it appears that the CX-5 retains the last reading taken before it was parked and is very slow to react when the engine is restarted even though it may be several hours later and the outside air temp might have changed by + or - 15 degrees.

I seem to recall that the display readout is buffered by software and is programmed to delay giving new readings until it figures the car has traveled far enough for the thermocouple to stabilize. But I can't remember where I heard this and whether it applied to the CX-5 or another vehicle. I don't pay any attention to it until I've been driving some distance.

If you want to know what the ambient outside temperature is, one of the worst places to put the thermometer is anywhere on a parked or slow moving automobile. Of course the flat roof of a bank is not much better. But mine is accurate to within 1 degree once it has stabilized and the car is not in stop and go traffic. My Volvo stabilizes a little faster and my Ford is the least accurate of the bunch. But don't assume the bank's display is accurate just because it is so big and new looking. In the area I live they are laughably inaccurate - probably not a good place to judge the accuracy of your cars thermometer.

I find the Mazda's and Volvo's thermometer a very useful tool to assist in determining the likelihood of ice forming on the roadway when taking trips in winter weather. This is particularly helpful as evening sets in because it can keep me appraised of how fast the temperature is dropping. Just be aware that due to certain phenomena it is possible for ice to form on the roadway at ambient temperatures slightly above freezing due to evaporative cooling and that under other conditions ice will not form until the ambient is well below freezing due to residual de-icer on the road and/or ground heat. The thermometer in my F-150 is not very confidence inspiring and it not nearly as useful because it is all over the place.

 

[HandA]

Mine does the same thing. At first I figured it was like MikeM mentioned that it waits a bit to change from the prior temperature to the new one but 45 minutes renders it somewhat useless. And I'd be worried it might be as slow to react to cold in which case it could be reading well above freezing as ice is forming on the roads.

I don't expect it to be super accurate but I've had it read 15-20 degrees low for 30-45 minutes on a regular basis. The more drastic the temperature change the more it seems to confuse it.

 

[erhayes]

My last 3 vehicles with ambient temp gages required driving about a mile before the "good" temp was reached and stabilized.

 

[atitus]

Mine seems to be overall pretty accurate, but it does take a while to get there. I'm not sure if its an issue with the thermometer itself, or the frequency in which the temperature is sampled by the electronics. I'm actually far more annoyed when outside thermometers at the house aren't accurate, since I really want to know what the temp is before going out. With the car, I have already gone outside to get in, so I know what the temperature is like.

 

[HandA]

Mine will bounce between two numbers quite rapidly at times so it seems to sample quite often. When the temp is just right it will fluctuate several times a second.

My guess is that they overdid the delay that MikeM mentioned. I can see some use for it to avoid having it read crazy high after it has been sitting in the sun on hot blacktop for hours but it seems to wait way too long to start reading the actual temperature.

 

[BillB15]

Mine is definitely 2 degrees off. My old Honda Ridgeline had a setting to put a fluff factor into the reading to set it accurately to known outside temperature. Another Mazda loss to Honda technology.

 

[HandA]

Mine usually reads a few degrees high but I figure just above the surface of the black road it is probably hotter than in the shade somewhere.