Ambient air temperature sensor

[Romanoaf]

If your temperature isn’t displaying correctly the cause is likely a bad thermistor located in your right mirror housing.

FCA won’t sell you the sensor on its own, so you have a few options.
Buy a mirror assembly for around $100
Buy a used mirror assembly from a scrap yard, hopefully for under $50
Buy a sensor kit from the OEM in Italy - www.elkab2.com for 28euro
Replace the thermistor for around $0.25 (10k ohm)

You can test the sensor by reading resistance across the sensor, should read 10kohms @25 degrees Celsius +\- 3%

I chose to replace the thermistor.
First you’ll have to remove the mirror, by folding in the mirror removing the lower plastic cover, disconnecting the harness and removing the 2- 5mm socket head screws

Next you’ll need to remove the mirror glass and plastic back cap, recommend warming up the plastic so you don’t break any clips.

You should then see the sensor:

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At this point you can decide whether or not to cut and solder the new thermistor or re-socket the connector.
I cut and soldered.
The sensor rotates counter clockwise to remove.
I dug the old thermistor out of the resin on the sensor, and re-potted the new thermistor with 5 minute epoxy

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Install in reverse, there is no polarity on the sensor or the heated mirror wires, so it doesn’t matter which way it’s soldered/ plugged back in.

[sportfan]

Good info ,thanks for sharing.

[texanbrit]

This is brilliant! Many thanks for sharing!

[MadFiat]

Wow I was just thinking about this since my 500 Turbo's sensor reads about 10 degrees low.

[Chef_B]

This is awesome, thank you for sharing!

Some important info that I learned: In the absence of input the computa assumes that its <freezing and runs very rich. If this is sensor is not reading accurately or you disconnect your passenger side mirror instead of leaving it dangling by the wires bc someone hit you and knocked it off your car, you should aim to address this as a priority for the sake of engine longevity.

[Dsouza]

The sensor can be bought on eBay instead of replacing the entire passenger side mirror

https://www.ebay.ca/itm/124101669566

[dapascale]

Hi all! Bringing this post back from the dead!

My wife and I recently purchased a 2014 Fiat 500L Lounge and have already started experiencing this problem. We've had a hot summer, and those days when the reading is off and our car tells us there are 'Possibly Icy Roads' means we have been dying without AC.

We can't afford the $700+ quoted to us by the only Fiat service center nearby. Would anybody who has fixed the sensor on their own be willing to give me a tutorial of sorts? One written for a real simpleton? I'd also be open to a phone call if that is easier for some than typing everything out.

Thanks!

+ Daniel

[torresdd]

Hi dapascale

Did you ever get a response to your question? I too have a 2014 500L where the outside temperature varies widely and doesn't show the correct temperature. I have ordered the replacement part from here, https://www.ebay.ca/itm/124101669566 but it says deliver date is anywhere from 7/Nov to 3/Dec. I will let you know what I do when I replace it.

===============================UPDATE============================================================================
Got the part in yesterday, 27/October/2021. It came from the Russian Federation. Waiting to isntall.

[Dsouza]

I ordered the part as per the post. Cut the old sensor off. Retired the new sensor wiring. The temperature gauge on dashboard reads nothing and check engine light shows up. Used a scanner to find out code and it shows p0071 and p0074

[texanbrit]

I ordered the part as per the post. Cut the old sensor off. Retired the new sensor wiring. The temperature gauge on dashboard reads nothing and check engine light shows up. Used a scanner to find out code and it shows p0071 and p0074

You probably need to test the thermistor.

"You can test the sensor by reading resistance across the sensor, should read 10kohms @25 degrees Celsius +\- 3%"