Problem with the charging system. Have the system tested at your local auto parts store. Most will check it for free.
It could be a bad alternator, worn belt or the belt tensioner itself was bad.
Why would battery light come on then go off
altenator
Replace your alternator
Take off the negative battery cable and hook a test light in between the cable and the battery post. If you have a drain, the light will be on. Start pulling fuses until the light goes off and when it does go off, that is the thing that is draining the battery. If no fuses affect it, take the altermator wires off. If the light goes off then, the alt is bad,.
Reset the check engine light on a Ford Fusion by disconnecting the battery. On newer cars, once the battery is reconnected, the light will come back on. If this happens, disconnect the battery, turn on the headlights until they go off, draining all the electrical current from the capacitor. Reconnect the battery and the light will go off.
Clean both battery cables and check the connections on the alternator. If it continues, go to auto zone and have the alternator checked.
disconnect the positive battery post and wait five minutes , then reconnect battery. The light should go out
triple diodes in alternator are bad
disconnect the battery for 1min or so the light will go off
light should go off . if that was the problem, and is now fixed, disconnect the battery for 5 minutes,then reconnect battery this will reset the computer and remove the signal from the warning light if that doesnt work, there is a different problem apart from crankshaft sensor
Replacing the battery should not have triggered the check engine light. The check engine light comes on when there is a problem with the emission system. Saying that, I would drive it for a while to see if the light does go out. If the light does not go out have the ECU scanned to retrieve the trouble code. Then use this code to diagnose the problem.
usually means that the alternator is not charging. So the battery is being drained.