My wife went to fill up the car with gas. When she left the gas station, the CEL came on and also the snowflake warning (for possible ice).

Thing is, it's 90 degrees outside here in North Carolina. The external temperature reading says it -40 degrees.

CEL is P0073

Any ideas?

 

I am gonna say your ambient air temp sensor has failed, or the wiring has been damaged. -40 is the "default" number, IIRC.

 

If it's just the ambient air temp sensor, why would that trip the CEL?

 

The ECM uses that information for calculating things like fuel mixture, I would imagine. I know that when my wife's 2013 Justa Convertible had that code, it was because some critter chewed the wires leading to that sensor, and the MIL came on with a P0073 code.

 

Thank you. I need to find a thread on how to replace the ambient temp sensor...

 

On my 2011 MCS and my wife's 2013 Justa, it is kinda under the front bumper, actually comes a little bit through a hole in the bottom of the bumper cover. On the right (passenger) side, IIRC. I was able to reach it by jacking up the car and reaching into the underside of the bumper cover.

 

^This. If you lie on the ground, the temp sensor is on the underside of the bumper, almost directly under the fog light. Removing the fog light access panel in the wheel well, you can gain access to the sensor and harness through the access hole.