Any way to adjust outside air temp reading?

not that i have read

 

2 degrees too high from what? What you are hearing on the radio? The temp sensors are mounted pretty low to the ground - at least on all the Toyota and Lexus vehicles we've owned.

I've got several cell phone apps that provide the outside temperature. They rarely agree. 2 degrees off from what you think it should be sounds great.

 

Make sure it's seated in it's correct place.

 

It can be adjusted + or - 2 or 3 degrees, but it can only be done by the dealer or if you have the Techstream software or an OBDII reader that includes that function. In any case, the sensor is mounted pretty low to the ground and will not necessarily reflect actual air temperature, particularly in the warmer months where it senses heat from the road. My advice would be to forget about it, it won't have any major impact on the climate control system.

 

Ya beat me to it! I was going to say the same thing. Techstream, but not worth the bother.

 

yes, that i have read

 

The Carista smartphone app contains the following customization option. Should be easier than using Techstream or the dealer. Ambient temperature calibration
-3°C / -2°C / -1°C / *NORMAL* / +1°C / +2°C / +3°C

 

2 Degrees higher than what?

 

Good point. Three different thermometers will likely give three different readings.

 

How do you determine "ACTUAL"? Hold a thermometer out your window? Are you measuring the temperature at the same elevation as the sensor on the front of the car as you drive? My wife and I have several weather apps on our cell phones and they rarely agree on the current temperature.

As a pilot, you must know that air temperature is highly dependent on altitude and be familiar with how blazing hot a hard surface runway can be. I've frozen my arse off on hot summer days before exiting the open doors of aircraft in flight and until I "fell" to lower altitudes.

 

Any way to adjust outside air temp reading?

TLR
Yes...and it's fairly easy, but it is unnecessary for nearly everybody.


Reader's Digest Version:

Yes.
Take the bumper off of your car and solder a biasing resistor in series or in parallel with your car's ambient air sensor after using a multi-meter and a potentiometer and taking some measurements. If you're lucky, your temp sensor will just need something like a 1-2k resistor soldered in series with the temp sensor, presuming it uses a negative temp coefficient thermistor and you think it's reading a few degrees high.
It's a completely passive, 2-wire sensor and it will not harm anything if you tinker with it.

....or if you think that yours is defective - simply replace it for $15 plus labor.
I strongly recommend you DIY this for two reasons:

1. Your sensor is almost certainly not defective.
2. See the video.


Full BULL version....

ACTUAL temperature depends on several things, and probably one of the more important of these is actually where you actually are.
If you want an estimation of the outside air temperature, you're going to need a device called a thermistor that is placed somewhere on the outside your car.
The tricky part of course....is WHERE to put it, because "outside air temperatures" vary.
Roads are hot.
Engines are hot.
The roof may be relatively cooler or hotter depending on color.

When you look down at your phone, hopefully if you're not driving, you may have a local weather app enabled which shows you the outside air temp in your town. This is often taken from your local ASOS data (no....not the fashion company)
Automated Surface Observing System (ASOS)
Being a dot.gov system it's fantastically expensive, and politically charged since ASOS serves as a primary climatological observing network in the United States, and as we ALL know.....weather IS climate...and climate IS weather.

Drifting notwithstanding, you can (and people do) get the "local" outside air temp from this system.
Pilots get air temps from this system in their ATIS reports, and the NWS uses this information in like manner.
Because: NOAA
Sometimes if some of your town's newsies have a particularly geeky weather department, they will provide local temps from other sources.

Almost all of this wonderful information comes from a little dab of 'powdered metal oxide' (rust) with 2 electrical leads called a thermistor.

A thermistor is a passive device, that literally, costs just a few centavos.
They look something like this:

But they're usually molded into a BLACK plastic housing that looks like this:

Like everything else in the world, you can get one delivered from Amazon in a few days (more during pandemics) and they're about $15
In a Prius, they're located in the nose of the car right in front of the radiator.
REPLACING one is simplicity itself.
....you just need to take the bumper off of the car! (for a G3)
It's not as bad as it sounds and it's fairly easy to DIY - but it's one of those repairs that will probably cost you well over $200 from a dealer.

Still with me?
Wow....
So....Thermistors are one of those things in life that work really well, and because of modern (automated) manufacturing they're VERY consistent, which is important because you want your 72 degrees to be the same every time the thermistor is at the exact temperature that it is when your instrument says it's 72 degrees.

We used them in the submarine service extensively because temperature is one of the things that can affect how sound propagates through water, and that's fairly important....but that's just one very obscure example.

They're so widely used in society today that right now, as you're reading this there are probably several of them within a few feet of you quietly doing their thing.........

 

As there is no way to adjust it in the settings, wouldn't it be easier just to subtract 2 from the reading if you know it's 2 degrees out ?

 

2-degrees out from WHAT?

 

From what the OP "believes" to be the real outside temperature.
FWIW, I believe mine is spot on at 131 ft above sea level where I live.
When it shows 0 deg C or less there's a frost on the ground, that's good enough for me.
I know to take it easy when it shows 4 deg C or less as there is a possibility of black ice in shaded areas (can't remember where
I got this info from many years ago though).

 

wow ... now THAT'S a reply!

 

Cycling outside yesterday, one of my riding partner's computers shows the temperature. It would alter based on if we were in direct sunlight, or if the sun was behind the clouds. It's not that the ambient air temperature was changing much (the 'feels like' temp was 103 degrees for a while), but the sensor was reacting to the sun exposure (possibly with the extra UV / Infrared that was hitting it).

I imagine that it would have to be a really well hidden and protected sensor to read the 'correct' temperature, as being close to any piece of bodywork that was directly exposed to the sun would alter a temp reading.

 

mine is pretty accurate, always 2 degrees below what the phone reports. takes a long time to adjust though.

 

I don't know if the outside temp really changed that much, but a few days ago when I was driving out of town about 20 miles, the temperature reading fluctuated rapidly between 80F to 96F. I don't think I have seen that rapid changes in my 2017 PRIME. Maybe new 2020 PRIME has more sensitive sensor?