2002 GMC Yukon won't start

Hi:
You will need to have it happen again. Chances are the starter may be the problem, but there other things that could cause it too, a relay, ignition switch, connections.

However, when it's working fine, there is no way to tell. If you want to check it, the next time it does it, have a helper turn the key to the run position and check if you're getting power to the small wore on the starter. If you get power, the starter is bad. If no power, the problem is up stream, relay, switch.

Joe