Before running down the rabbit hole of possibilities and numerous error codes, stored for retrieval by regular scanners while hidden errors are only decoded by Subaru's SSM scan tool, repair/mobile techs/diyers spending more for moderate to high end scan tools, is your battery original or on its second one and haven't tested it yet? And are battery connections clean and free of corrosion, including main grounds to chassis and engine block? And after testing your battery, have the alternator tested too. Most auto stores selling car batteries can test batteries and alternators on the car (Autozone is one). If testing at home with a multimeter, some things to know.

Standing battery voltage should be around 12.5vdc. Engine idling, serpentine did belt tight, alternator output should be around 14.5vdc. Voltage below 13vdc suggests either a loose drive belt or faulty alternator.

Average battery life is between 3-5 years. More money buys more battery life and vice versa.

 

Thank you for your prompt reply. I did disconnect the battery posts and clean them well with water and baking soda once I had both posts disconnected. I held the 2 posts together for 20 seconds to reset the E. C. M, but that did not work. I will have the alternator tested tomorrow and check all the drive belts as well. Again, thank you for your input.

 

All goods suggestions. Remember subaru has a smart charging system. The alternator stops charging the battery when battery is at full charge. I believe even on the 2016

 

Thank you, kindly!

 

When my 2014 did that, it was the dreaded CVT valve body replacement.

 

Thank you. Duly noted.