Outside Air Temperature Discrepancy

[Mach1E]

I was told by phoenix ford dealership, it appears to be a programming issue ford engineer was working on the programming. to fix it . mine was reading 130 when it was 105 outside.

Go put your hand on the ground under your car and see if it feels 105 or 130.

It may be 105 in the shade, but 130 in the parking lot.

I don’t think it’s an error, it’s just reading the temperature below your car.

Never once have I found a thermometer to be 25 degrees off.

The car is NOT giving a weather forecast.
It’s just got a thermometer. And yours read 130 when it detected 130 degree air.

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[cjfarmer]

Go put your hand on the ground under your car and see if it feels 105 or 130.

It may be 105 in the shade, but 130 in the parking lot.

I don’t think it’s an error, it’s just reading the temperature below your car.

Never once have I found a thermometer to be 25 degrees off.

The car is NOT giving a weather forecast.
It’s just got a thermometer. And yours read 130 when it detected 130 degree air.

my truck parks next to it and its a 2021 F150 it reads the correct temp. and my GT 5.0 reads the same temp as the weather. so, it make me beleive it the car issues like everything else with the Mach E programming issues.

 

[macchiaz-o]

my truck parks next to it and its a 2021 F150 it reads the correct temp. and my GT 5.0 reads the same temp as the weather. so, it make me beleive it the car issues like everything else with the Mach E programming issues.

Or their sensor is higher up, or some other non-programming related difference.

 

[Mach1E]

my truck parks next to it and its a 2021 F150 it reads the correct temp. and my GT 5.0 reads the same temp as the weather. so, it make me beleive it the car issues like everything else with the Mach E programming issues.

Sensor location.

Can’t put a temp sensor under the car on an ICE. Would read 170 degrees from the engine heat!

 

[SnBGC]

Or their sensor is higher up, or some other non-programming related difference.

^ This is the correct answer.
The sensor on the Mach-E is only 16" from the pavement. And it's pretty hot down there. Much higher temps near the road surface vs higher up. Even 60" above grade is much cooler than 16".

Based on this ASU study,
https://www.phoenix.gov/streetssite/Documents/Phoenix Cool Pavement Exec Summary_091420213.pdf
The valley is embarking on various programs to "cool coat" the hardscaped surfaces. This basically increases the reflectivity and makes us slightly more uncomfortable during the day but cooler at night. This results in an overall reduction of the Heat Island Effect. (My son just explained this to me since he has degrees in this sort of thing.....).

 

[SnBGC]

So check this out....
It appears Outside Air Temperature as reported by SOBDCM C is actual ambient. We tested it on the drive home. Check my process and let's see if you agree with my conclusion.

I followed my nephew in his 2020 Ford pickup on the way home. My son rode along with him and texted me with updates to their temp display in the truck.

Started our vehicles and my reading was 91F while theirs was 86F. Within a couple hundred feet of driving, my reading matched theirs (86F). Then they both tracked together. Pulled out onto the road in front of our shop and temps increased to 88F. Freeway on ramp was 91F. Stuck in traffic on 1-10 at 93F and stabilizing at 95F.

Clear the congestion and drops to 90F. The section of US-60 that flies over the train tracks drops to 88F.....both vehicles. Then back to 90-91F for the remainder of the 20 mile drive.

I data logged most of the trip. Will sort through the data and see what info (if any) that jumps out at me.

Data captured is
1. Outside Air Temp
2. Generator Inverter Voltage
3. Generator coil temp (not a real value)
4. Transmission fluid temp
5. Motor inverter voltage
6. Motor coil temp (seems valid)
7. APP
8. HVB current
9. Hybrid Electric Vehicle Traction Battery Thermal Operation Level (what just curious what that was about....)


So, do we agree there is a value in the SOBDCM C that knows actual ambient temp? If so, how does it determine that value? Seems fairly accurate.....for today's drive at least.

Oh BTW....the Sync screen started at 95F and stayed that way for about 5 min then it rose to 100-101F and consistently remained 8-10 degrees F above whatever the SOBDCM C was reporting as actual outside Air Temp.

 

[Mach-Lee]

So, do we agree there is a value in the SOBDCM C that knows actual ambient temp? If so, how does it determine that value? Seems fairly accurate.....for today's drive at least.

Oh BTW....the Sync screen started at 95F and stayed that way for about 5 min then it rose to 100-101F and consistently remained 8-10 degrees F above whatever the SOBDCM C was reporting as actual outside Air Temp.

Yes, seems like the actual temp but it has to come from the ECM/PCM since the SOBDMC doesn't have an ambient temp sensor wired to it. Only motor temp and trans fluid temp.

The service manual lists this for the SOBDMC:

Ambient air temperature filtered (source: ECM) - Ambient air temperature, used to adjust high voltage battery cooling fan speed

Still no idea why the display would show a much higher reading than what you saw on the scan tool. It should have come down to match if you were driving for 5 mins.

 

[SnBGC]

Yes, seems like the actual temp but it has to come from the ECM/PCM since the SOBDMC doesn't have an ambient temp sensor wired to it. Only motor temp and trans fluid temp.

The service manual lists this for the SOBDMC:

Ambient air temperature filtered (source: ECM) - Ambient air temperature, used to adjust high voltage battery cooling fan speed

Still no idea why the display would show a much higher reading than what you saw on the scan tool. It should have come down to match if you were driving for 5 mins.

Thanks for that extra info. HVB cooling fan is a funny description, but I get what they actually mean there.

To clarify......
I have found air temp in three different modules so far...

1. PCM: Listed as Ambient Air Temp and it shows the sensor voltage as well as temp value
2. HVAC: Listed as Filtered Ambient Air Temp and it showed the same temp value as #1
3. SOBDMC: Listed as Outside Air Temp.

# 1 and #2 match what is shown on my sync screen. That value did change after driving for about 5 minutes.
#3 was a different value and was static until I put the car into motion. After a couple hundred yards it began to show a different value that matched almost exactly to what my nephew was showing in his pickup while we both drove on the same road at the same time. We drove for about 20 minute and it tracked the same throughout that drive. It amazes me that value was so accurate or at least in alignment with what his truck was reporting as ambient temp so I am super curious how that value is determined.


I believe the display gets it's value from the HVAC module, which says it is "filtered" (whatever that means....). I did look at the HVAC PIDs and found a setting for Filtered Ambient Temp. That value matched the Ambient Air Temp sensor in the PCM at the time I looked at it so I don't really know what filtered means. Does that mean it is sampled less frequently, or perhaps the value is adjusted by a factor or equation or maybe even something else entirely? ?

 

[jmatero]

So I have the same thing going on right now and it is a new problem. Up until a few days ago, the ambient temp displayed was accurate the second the car was powered on and the AC was always cold. Suddenly, my car in the afternoon (90-100 degrees out) shows the ambient temp at the last drive that morning (62) and therefore will not cool the car. I have to drive a few miles and suddenly it quickly jumps up to the correct temp. Bad ambient air sensor? System issue? Really sucks because even on max ac the car will not cool because it thinks it's in the low 60s on a 100 degree day.

 

[Ford Motor Company]

So I have the same thing going on right now and it is a new problem. Up until a few days ago, the ambient temp displayed was accurate the second the car was powered on and the AC was always cold. Suddenly, my car in the afternoon (90-100 degrees out) shows the ambient temp at the last drive that morning (62) and therefore will not cool the car. I have to drive a few miles and suddenly it quickly jumps up to the correct temp. Bad ambient air sensor? System issue? Really sucks because even on max ac the car will not cool because it thinks it's in the low 60s on a 100 degree day.

Hello, John! Send us a private message with your VIN and the name and location of your local Ford dealer. I’d be happy to see what I can do to assist with this Air Conditioning concern. Thanks!

 

[Fixbear]

The bumper sensor is called the ambient air temperature (AAT) sensor and is actually wired directly to the PCM. The PCM reads the value and sends out the reading to all the various modules on the CAN busses. There are no other ambient temp sensors outside the cabin or under the hood. Only coolant temp sensors.

The temp reading parameters will not update when the car is stopped. Basically I did an experiment where I blew a heater on the outdoor temp sensor with the ignition on, and none of the readings changed anywhere. It continued to use the last temp reading from the last time the car was driven, even though everything has fully cooled down (parked for 12+ hours and garage was ~15ºF cooler than last reading). Nothing in the car was as warm as the last reading.

The current software will not update the outdoor temp unless the vehicle starts moving, I think the spec is you have to drive above 20 mph for at least 90 seconds before it will update. Below that speed it probably uses the last value.

I will have to double check the outdoor temp reading in the SOBDMC again, IIRC that didn't change on my car but it seems to on yours. Perhaps that is a difference with the newer software. Yours might not have the averaging algorithm on everything while stopped.

I think the PCM is still sharing the live AAT readings in the background, that's why the SOBDMC was updating even though other indications weren't? It's not because it has it's own sensor. You can try the hairdryer test too while parked to see what changes and what doesn't.

So what does the sensor in the rear hatch LS seal do? I thought it was a heater when I replaced it, but Parts said it was a sensor.

 

[methorian]

So I have the same thing going on right now and it is a new problem. Up until a few days ago, the ambient temp displayed was accurate the second the car was powered on and the AC was always cold. Suddenly, my car in the afternoon (90-100 degrees out) shows the ambient temp at the last drive that morning (62) and therefore will not cool the car. I have to drive a few miles and suddenly it quickly jumps up to the correct temp. Bad ambient air sensor? System issue? Really sucks because even on max ac the car will not cool because it thinks it's in the low 60s on a 100 degree day.

This is how mine has always worked, and it's incredibly frustrating for HVAC controls. I've always assumed it was just bad design/programming on their part.

When I get to work in the AM it may be 60F out. During the day it jumps to 92F out. I remote start the car about 15min before I leave. I get to the car and it's still pretty toasty inside and the temp reading still shows 60F. Auto HVAC isn't doing much. Drive about 5 minutes and suddently the AC is blasting since it now shows 92F out. It's pretty damned annoying! I even brought it up to my dealer at one point but was just told that's "how it works".

 

[dbsb3233]

While it's nice to see the car temp, most people assume the temp on the screen is supposed to be outside ambient temp instead.

I have Android Auto on all the time. It shows the temp from nearby weather stations. It's often 10 degrees different, but sometimes it's close. I usual go by AA instead.

 

[Mach-Lee]

So what does the sensor in the rear hatch LS seal do? I thought it was a heater when I replaced it, but Parts said it was a sensor.

LS seal? Probably a pinch sensor.

 

[pottslaw]

While it's nice to see the car temp, most people assume the temp on the screen is supposed to be outside ambient temp instead.

That was one of my basic concerns when I started this thread more than a year ago. The temperature near the pavement is important for the battery and cooling systems, but (1) irrelevant (and misleading) to the occupants of the car and (2) inconsistent with every other Ford vehicle I have owned. I have learned to live with it (Phoenix is hot!) but I still think it is a glaring weakness in the design of the car.

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