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2021 ram limited showing wrong temperature

6of36

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I always find it funny when people quote what they paid for their trucks, as if it somehow makes a difference. It's made on same assembly line as much cheaper trucks, utilizing 90% the same parts. Just like you said
When they build a quarter million a year, there are bound to be a couple defective parts. I think in the last 25 years, out of the more than a dozen new vehicles I bought, I had 1 vehicle that didn't have some minor warranty repair.
 

theblet

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Every vehicle I’ve driven doesn’t show the correct outside temp until you drive it for awhile. Ford, Chevy, dodge, Kia, etc. and even then it’s not perfect.
 

HSKR R/T

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Every vehicle I’ve driven doesn’t show the correct outside temp until you drive it for awhile. Ford, Chevy, dodge, Kia, etc. and even then it’s not perfect.
I still ask what are people using to "verify" correct outside temp for where the truck is at.
 

theblet

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I still ask what are people using to "verify" correct outside temp for where the truck is at.
For me, my outdoor patio thermometer, and weather apps on my phone. none of them will be exactly the same. The vehicles give you a good idea of what the temp is, but you have to drive for a bit.
 

HSKR R/T

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For me, my outdoor patio thermometer, and weather apps on my phone. none of them will be exactly the same. The vehicles give you a good idea of what the temp is, but you have to drive for a bit.
Yeah, as I mentioned previously, the weather apps can be just as far off because they might be 15-20 miles, or more, away from your location. Which can make a big difference in air temps. I have the SiriusXM weather showing on my 12" as well as outside temp sensor reading. I've seen them up to 15 degrees difference, but I'd trust the outside air temp reading to be more accurate to where I actually am than the weather app. Most of the time they are within 5 degrees of each other. It's kind of like rainfall amounts. Saturday the "official" rain total for Omaha was .001" measured at Epply Airfield. But not three miles away they had over an inch of rain.
 

WXman

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There are tons of threads on this.

You have to drive the truck down the road for at least 5-10 minutes. That will give the sensor time to acclimate to ambient temp with wind flowing over the sensor. Once they moved the sensor to the driver side mirror this became a problem. It gets sun soaked and reads hot. Takes a good long while of airflow over the sensor to acclimate it.

If you have a mesonet in your state, look up their website and find the weather station closest to your location. Use that to judge how accurate your thermometer is. Never rely on stuff you see in a weather app. Weather apps suck. Use official stations only. Airport ASOS, mesonet sites, NWS offices, etc. I do this stuff for a living. Bad readings on weather instruments bother me. :D
 
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HSKR R/T

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There are tons of threads on this.

You have to drive the truck down the road for at least 5-10 minutes. That will give the sensor time to acclimate to ambient temp with wind flowing over the sensor. Once they moved the sensor to the driver side mirror this became a problem. It gets sun soaked and reads hot. Takes a good long while of airflow over the sensor to acclimate it.

If you have a mesonet in your state, look up their website and find the weather station closest to your location. Use that to judge how accurate your thermometer is. Never rely on stuff you see in a weather app. Weather apps suck. Use official stations only. Airport ASOS, mesonet sites, etc. I do this stuff for a living. Bad readings on weather instruments bother me. :D
Moving it to the mirror didn't create the problem. The same thing happened when it was behind the grill. The only difference is, with it on the mirrors now you don't have the heat from radiator screwing with the reading while parked.
 

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Moving it to the mirror didn't create the problem. The same thing happened when it was behind the grill. The only difference is, with it on the mirrors now you don't have the heat from radiator screwing with the reading while parked.

I disagree.

On a cold start with the sensor behind the radiator you get perfect readings immediately, which means your climate system knows what to do immediately. Very few people sit in an idling vehicle for an hour. So the sensor is accurate more of the time in this location. No affect from sunlight.

But with it moved to the mirror, now you get extremely erroneous readings as soon as you walk out to the truck regardless of how long it's been sitting. This throws off the climate control also, since it partially relies on that exterior reading to control ambient on the inside, along with the inside sensor behind the dash. In this case, the ONLY time the sensor is accurate is when driving at speed.

I would take a location in front of the radiator any day of the week.

Taken from an ASE study guide:

autotempsensor.jpg
 
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HSKR R/T

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I disagree.

On a cold start with the sensor behind the radiator you get perfect readings immediately, which means your climate system knows what to do immediately. Very few people sit in an idling vehicle for an hour. So the sensor is accurate more of the time in this location. No affect from sunlight.

But with it moved to the mirror, now you get extremely erroneous readings as soon as you walk out to the truck regardless of how long it's been sitting. This throws off the climate control also, since it partially relies on that exterior reading to control ambient on the inside, along with the inside sensor behind the dash. In this case, the ONLY time the sensor is accurate is when driving at speed.

I would take a location in front of the radiator any day of the week.

Taken from an ASE study guide:

View attachment 160281
My experience with vehicles with sensor behind the grill, they suffer from heat soak in the sun as well. my 00 Dakota has sensor behind the hrill. on hot days, even with cold engine, I have gotten in and seen temps up to 120 displayed until I started driving. add in hot engine after parking for a little bit and I've seen130+. And not every start us a cold start. Drive to a store on a 90+ degree day, spend an hour in the store, and your engine) radiator are still hot.
 

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I think they will heat soak no matter where the sensor is if it’s a sunny day. To me, the black mirror housing will heat up faster tho. The best place for temp would probably be under the truck, but the sensor wouldn’t last very long down there
 

kdoublep

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I hold a wet finger out the window to judge temperature and wind speed. It's calibrated by the American Institue of Engineers to be dead on balls accurate. 0 variance.
 

HSKR R/T

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2018 RAM Promaster City. Temp sensor behind grill. Has been sitting outside all day, engine not running, picture taken after driving a block. Actual outside air temp is 87 according to weather app. Second picture is after driving 10 miles. PXL_20230606_185710421.jpg PXL_20230606_191528208.jpg
 

HSKR R/T

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After sitting for 1/2 hour engine not running
PXL_20230606_202004965.MP.jpg
 

RC Turner

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What you are reading is the temp of the road. The air over the road is warmer than the air over water, grass, etc. Go stand on the asphalt in the sun for a while. You will quickly see the issue.
 

6of36

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Obviously OPs truck has a bad thermister ( what the sensor actually is ) if his is 10 degrees hotter, no matter what, but no matter where it is mounted, you have to drive to get an actual reading, and the road surface can make a difference. You could place a thermometer 10 ft off of the road, and it will read different than one in the middle of the road.
 

Topsella40

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I always find it funny when people quote what they paid for their trucks, as if it somehow makes a difference. It's made on same assembly line as much cheaper trucks, utilizing 90% the same parts. Just like you said
I wouldn’t expect a 80 k truck to have the same parts as a 40 k truck..lower models.with that price point you would think some more quality parts
 

6of36

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I wouldn’t expect a 80 k truck to have the same parts as a 40 k truck..lower models.with that price point you would think some more quality parts
With a higher price you will get a better interior, and more options, but the base parts are all the same.
 

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