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Discussion Starter #1
It started randomly about 6 months ago when it was still hot, that the outside temp in the gauge display started reading low, just about 10-15 degrees lower than it actually is. It hasn't really bothered me, but I thought I should ask, since here you are, a whole bunch of Fiat 500 owners, has any of you experienced this issue. If so, what's the cure? I was wondering if I should just disconnect the battery and that should reset the thing, right?
 

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It started randomly about 6 months ago when it was still hot, that the outside temp in the gauge display started reading low, just about 10-15 degrees lower than it actually is. It hasn't really bothered me, but I thought I should ask, since here you are, a whole bunch of Fiat 500 owners, has any of you experienced this issue. If so, what's the cure? I was wondering if I should just disconnect the battery and that should reset the thing, right?
Mine is off by about that much as well. It reads too cold in the winter and too hot in the summer. Incase you don't know, the sensor is underneath the passenger door mirror, maybe make sure it's clean and in place??

Interested in a resolution, for now I just live with it.

Jon
 

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It’s not really actuate, while driving. It read hotter, when the suns on it. It’s not even actuate in the garage, sitting there. I rely on my watch, or phone for the temperature. Our other brand cars do the same thing. False readings. Their close. But off.
 

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Matches the accuracy of the indicated range
I went on a 60 mile trip today, and when I left, the range was reading 60 miles.

60 miles later, guess what my range was...

60 miles.

Boom. Most fuel efficient vehicle ever.

On the plus side though, I drove it out of sport mode to save fuel- something that never happens.

Jon
 

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I know this is an older post but for future on lookers the issue is the ambient temperature sensor which is located in the passenger side mirror. Requires a replacement mirror.
 

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I know this is an older post but for future on lookers the issue is the ambient temperature sensor which is located in the passenger side mirror. Requires a replacement mirror.
Whomever designed that thing should be flogged. Like no one has ever had to replace a temp sensor!
 

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Ive started having an issue with mine. It doesn't happen all the time and I cant figure out what triggers it. Seems to happen When I open and shut the hood. First time it was like 55 and it started reading 31 degrees. Which set the ice warning and so on,No biggie. However, last night was a huge problem. 75 degrees here in Texas and the temp gauge was reading 22 degrees. So when I turned on the AC it would not blow cold because it thinks its cold outside. I was idling the car and had opened and shut the hood. Once I started moving after about 5 minutes the temp corrected its self and the AC started cooling.
 

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Ive started having an issue with mine. It doesn't happen all the time and I cant figure out what triggers it. Seems to happen When I open and shut the hood. First time it was like 55 and it started reading 31 degrees. Which set the ice warning and so on,No biggie. However, last night was a huge problem. 75 degrees here in Texas and the temp gauge was reading 22 degrees. So when I turned on the AC it would not blow cold because it thinks its cold outside. I was idling the car and had opened and shut the hood. Once I started moving after about 5 minutes the temp corrected its self and the AC started cooling.
Yes, we're now having the same problem. It registered for a time this afternoon as -9 when the outside temperature was in the upper 89s. And, like your situation, it kept the AC from cooling. After 5 or 10 minutes it started reading correctly and the AC could, once again, work. Just hope this doesn't get to a point where it doesn't finally correct!
 

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It doesn't always require a mirror replacement. The glass can be popped out and the sensor replaced. Finding a matching sensor is troublesome. One person replaced it from a broken mirror off eBay. Another cannibalized one from a Caravan (though didn't say how it worked afterwards). If I had painted mirrors, I might cannibalize a new factory mirror (or see if there's a part# on the sensor).
 

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The term "mirror" here is confusing. I just replaced a mirror--the actual piece of glass with the heater fused on to its back and two spade connectors. I couldn't see anything in the housing that looked like a sensor and the two wires that plug in to the spade connectors appeared to be for powering the heater on the mirror. The cost of the glass at the dealer was about $30. I assume the housing would be a multiple of that. Would this temp sensor perhaps live in the base of the housing?
 

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Yes, per Mopar, you bought "mirror glass", while they refer to a mirror as the entire assembly. It runs $65 to $100 (new) online. The sensor is a black piece, about the size of a pen cap, with 2 wires running to it, attached to the mirror housing. The complete description is usually something like:

PASSENGER SIDE DOOR MIRROR, CHROME, POWER, WITH HEATED GLASS, WITH TEMP SENSOR, WITHOUT BLIND SPOT
 

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I think if you even replace the sensor In the mirror. Your temperature readings, with still not be accurate.
Good Luck.
 

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Would this affect in any negative way? Like A/C or fan speed etc. I'm asking because mine does not read or read always under zero when it's about 70°F outside.
 

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Discussion Starter #16
Would this affect in any negative way? Like A/C or fan speed etc. I'm asking because mine does not read or read always under zero when it's about 70°F outside.
That outside temperature sensor is tied to the ECU, and is part of the data that determines the engine operation parameter, believe it or not. So if the temperature reading is VASTLY off, it can trigger CEL. Mine’s off just enough to cause CEL about twice a year, once when weather gets warm and once when it cools down noticeably. I don’t know what the parameter is, and mine chugs along without an issue otherwise, so I just clear the CEL and drive on. However, I did hear of some cases that the reading is so off that it causes a serious issue (like as if engine is trying to adapt to 110 degrees f when in reality the ambient temp is 48, or some such things).
 
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