[MaconPaul]

My 2009 N51 328i had a service engine soon light come on.
Autozone code reader says P0071 Ambient Air Temperature Sensor Range/Performance
It also says code P1515 but doesn't give more information.
In the More Information section they describe the Mass Air Flow Sensor which to my knowledge is not related to the 2 codes.
Note the car is running perfect. Perfect idle, good gas mileage. Dashboard temperature reads accurate. My son reports he has had the battery light come on upon turning off the car on rare occasions but not in the last month. The battery is of unknown age but is not new. Battery made by BMW and the connections are pristine.
Picture of the AutoZone code reader sheet attached.
What should I do?

[MaconPaul]

I disconnected the ground by the battery for 10 minutes and the check engine light stayed on when I reconnected the ground. Do you have to disconnect the negative from the actual battery to reset codes?

[Tunafish]

The maf sensor has the temperature sensor built in.

[MaconPaul]

I figured MAF measured temp too but there is a ambient temp sensor that requires the bumper be removed to replace. Does either code indicate MAF?

[MaconPaul]

CES light still on.
I'm reluctant to go replacing parts including the front bumper chasing a code.
TODAY I removed the Mass Air flow sensor and cleaned it.
I sprayed cleaner on the Ambient Air Temperature sensor just for good measure too. (The part that you can see through the lower grill)
I disconnected the negative battery terminal for 30 minutes.
Reconnected battery and the Check Engine Soon light stayed on. (Does this work w a e93? Am I doing it long enough? I don't have an OBD tool to reset CES light)
The dashboard thermometer has been spot on throughout.