As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE AT FL170 THE MANUAL CAUTION LIGHT ILLUMINATED AND COULD NOT BE RESET. THE PILOT DECIDED TO RETURN TO THE DEPARTURE AIRPORT WHERE IT LANDED SAFETY. POST FLIGHT TROUBLESHOOTING LED TO THE REPLACEMENT OF THE ENGINE ELECTRONIC CONTROL.