The most common cause of this issue is the alternator. However, as it was mentioned, there can be alternators that are "new" that are not charging properly. The only way to know is to perform a test on it.
Here is a guide that walks through this:
https://www.2carpros.com/articles/how-to-check-a-car-alternator
However, the real cause of these lights coming on is the vehicle's electrical system needs a minimum voltage to operate. The battery is there to stabilize the voltage that is produced by the alternator while the engine is running. When the engine is running the alternator can surge and under produce voltage at times so the battery smooths this out.
The battery will supply about 12.5 volts and the alternator will be around 14 volts. As mentioned if the belt is slipping, then the alternator will under produce voltage and the battery will slowly drain. Once this happens the vehicle will start load shedding items to try and keep the voltage up and it will turn these two lights on.
Please post questions if you are needing more info. Thanks
Wednesday, March 25th, 2020 AT 6:46 PM
