[highside907]

OK, I have searched the form for this answer, I have seen older threads about no display and 1 about reading high. Not my issue, I get in the car yesterday, I get the "caution ice may be present" message. But it's 65 degrees outside, I look at the temp on the dash and it reads -39? I drive around a while and go about my day. After 20 mins it starts climbing back to the actual temp. This morning it reads 32 climbs to 42 then in the fast food driveway drops to -19. Has anyone had this happen?

Car is a 2021 1SS

[sr71bb]

Originally Posted by highside907

OK, I have searched the form for this answer, I have seen older threads about no display and 1 about reading high. Not my issue, I get in the car yesterday, I get the "caution ice may be present" message. But it's 65 degrees outside, I look at the temp on the dash and it reads -39? I drive around a while and go about my day. After 20 mins it starts climbing back to the actual temp. This morning it reads 32 climbs to 42 then in the fast food driveway drops to -19. Has anyone had this happen?

Car is a 2021 1SS

That is probably a problem with the ambient air temperature sensor. It is a bitch to get to and requires the removal of front bumper. My was reading below ZERO as well in the past and we found out that it was a bad sensor. When this happens it will play havoc on the AUTO setting on your AC because it will want to turn on the heater.

[highside907]

Originally Posted by sr71bb

That is probably a problem with the ambient air temperature sensor. It is a bitch to get to and requires the removal of front bumper. My was reading below ZERO as well in the past and we found out that it was a bad sensor. When this happens it will play havoc on the AUTO setting on your AC because it will want to turn on the heater.

Yes it does. I was thinking that was the most likely cause.

[ctrlz]

-39 is the low limit.
Your ambient temp sensor likely failed open, which will result in it reporting the lowest temp.
Unfortunately, many systems require good data from this sensor.

DIAGNOSTIC INFORMATION AND PROCEDURES > DTC P0071-P0074: AMBIENT AIR
TEMPERATURE SENSOR > CIRCUIT/SYSTEM DESCRIPTION
The ambient air temperature sensor is located behind the grille. The engine control module (ECM)
monitors the ambient air temperature sensor utilizing a low reference circuit and signal circuit. The ECM
monitors the voltage drop across the sensor, which is inversely proportional to temperature. When the
ambient air temperature is cold, the resistance of the sensor is high. When the ambient air temperature
is warm, the resistance of the sensor is low. The ECM converts the voltage value to a temperature
value. The ECM also sends the temperature value to other control modules via serial data.

[highside907]

Originally Posted by ctrlz

-39 is the low limit.
Your ambient temp sensor likely failed open, which will result in it reporting the lowest temp.
Unfortunately, many systems require good data from this sensor.

DIAGNOSTIC INFORMATION AND PROCEDURES > DTC P0071-P0074: AMBIENT AIR
TEMPERATURE SENSOR > CIRCUIT/SYSTEM DESCRIPTION
The ambient air temperature sensor is located behind the grille. The engine control module (ECM)
monitors the ambient air temperature sensor utilizing a low reference circuit and signal circuit. The ECM
monitors the voltage drop across the sensor, which is inversely proportional to temperature. When the
ambient air temperature is cold, the resistance of the sensor is high. When the ambient air temperature
is warm, the resistance of the sensor is low. The ECM converts the voltage value to a temperature
value. The ECM also sends the temperature value to other control modules via serial data.

Thanks for the info. Looks like the dealer will be getting the car soon enough.