If the vehicle has a “Check Engine” light, connect a code reader to the diagnostic port.

If the P0562 code appears, it is very likely that the alternator is bad (keep in mind that the codes can vary depending on the make / model / year of the vehicle).

If a faulty engine alternator is suspected but does not have a warning light, raise the hood and check the condition of the belt.

If it is enameled and has a slightly burnt appearance, it is an indication that it is slipping.

The belt is too loose, so it slips on the pulleys instead of moving on them.

The friction of metal on rubber heats the belt, wearing it down quickly.

Does the tensioner need to be adjusted to get just the right amount of tension (too tight can also damage an alternator’s bearings), or is the belt simply serpentine.