Wife got home today in her 57 plate fiesta 1.25, lacking power and engine management light flashing, so i did the test using the trip meter and fault dtc 9312 came up.......googled that found couple posts saying its low battery volts and needs charging, told the wife then she said she left lights on all day while at work. Can anyone clarify thats the problem for that code. If so is it best to remove and charge the battery, or try n let it charge its self.

Any help would be great

Chris