Calibrate Ambient Temp sensor?

[AVC]

I did a quick search and didn't find a method to adjust the dash reported temp from the ambient sensor at the bumper. Mine reports about 5 degrees high (sitting in the shade for 8 hours, before I start the car). I have a copy of Forscan, but didn't see a sensor calibration in any body modules.

 

[madar]

You won't get an accurate reading until you're driving and have air blowing over the sensor for a few minutes. No calibration. It picks up heat off of ambient surfaces- engine heat, road surface, etc. at a standstill.

 

[AVC]

Well, that's true if the engine is running, or the car is in the sun, and the sensor is subject to that heat source. But overnight, , entirely out of sun exposure, before a start, everything is equalized to the same ambient. And it reads high.

How are you certain there is no calibration that can be done for the ambient sensor? Sounds like several dealers just said whatever to make the question go away. My Honda Pilot allows for +/- 9F, using a button press sequence.

 

[madar]

Did a search for you


https://www.mazdas247.com/forum/ind...ge-ambient-abberation.123850455/#post-6401991

 

[AVC]

Thanks. While I've found plenty of posts portraying the issue, none have posted a solution, other than buying another sensor and hoping it is more accurate.

 

[GAXIBM]

Why not move it to a cooler location?

 

[CX5_Driver]

Why not move it to a cooler location?

Let's review the parameters of the OP question. "...a method to adjust the dash reported temp from the ambient sensor at the bumper.. "

1) Car parked overnight (for the sake of argument in a garage). Car has not been run in eight plus hours; engine and all components are cool / ambient temperature.
2) Measuring the ambient air temperature in the garage (near the vehicle), the personal measuring device reads 80 degrees Fahrenheit.
3) Get into the Mazda CX-5; start the car; immediately review what the car "thinks/senses" the ambient temperature is. OP is stating the vehicle displays a temperature that is 5 degrees HOTTER on a consistent basis. That is the sensor in the vehicle is calibrated or not accurate to the ambient temperature.

The car was NOT previous running; there is no wind; and assuming the personal measuring device is accurate (perhaps more than one was used); how can OP CALIBRATE the ambient tempature sensor of the vehicle? Is there any adjustment to be made? Are the sensors simply "as-is" and you replace it hoping it is closer to accurate?

 

[AVC]

Correct, the sensor is reading 5F higher than it should, when *nothing* other than the ambient air temp is influencing it.. Moving it to a "cooler" spot won't fix the error.

As for moving the sensor to a cooler spot, in my experience, if an ambient sensor gets even 15mph ambient air flow across it for at least 30 seconds, that tends to insulate it from other radiant sources (radiator, engine, pavement...). It's why many OEM's warn that the ambient sensor isn't representative below 15mph or so. Or like Honda, it builds in logic to wait for 16mph + 60 seconds before allowing a *trending higher* temp update. It allows * trending colder* updates almost immediately.

 

[AVC]

UPDATE: As we had temps in the low single digits in NTX this week, I can confirm the ambient temp sensor was within 1F of WeatherUnderground local weather stations. Very pleased with the modification results!

 

[181962]

UPDATE: As we had temps in the low single digits in NTX this week, I can confirm the ambient temp sensor was within 1F of WeatherUnderground local weather stations. Very pleased with the modification results!

The modification was...?

 

[AVC]

Ambient Temp Sensor Tweaks 2017+

I dug around a bit to locate the ambient temp sensor (in front of the AC condenser to the right of the grill M emblem, looking into the grill). A good spot for the sensor to read ambient air once the car is moving above 15mph or so. Traced the sensor wires, where they wrap around the air...

www.mazdas247.com

 

[Magic Mel]

Correct, the sensor is reading 5F higher than it should, when *nothing* other than the ambient air temp is influencing it.. Moving it to a "cooler" spot won't fix the error.

As for moving the sensor to a cooler spot, in my experience, if an ambient sensor gets even 15mph ambient air flow across it for at least 30 seconds, that tends to insulate it from other radiant sources (radiator, engine, pavement...). It's why many OEM's warn that the ambient sensor isn't representative below 15mph or so. Or like Honda, it builds in logic to wait for 16mph + 60 seconds before allowing a *trending higher* temp update. It allows * trending colder* updates almost immediately.

Our CX-5 always reads 5 degrees high. Best car ever for reading was Dodge Neon RT which was always spot on. Our Acura ILX is adjustable from the display console. This is a Mazda-specific issue, and has potential to adversely impact a/c performance.