As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
During taxi, the crew reported a L/H engine fire. The crew shut down the L/H engine and activated the engine fire extinguisher. The aircraft returned to the gate without further incident. Maintenance personnel removed and replaced the L/H engine starter-generator. An operational check was satisfactory and the aircraft was returned to service.