As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 4984 - RECEIVED LEFT COWL ANTI-ICE MESSAGE. PERFORMED QRH, RETURNED TO CVG, LANDED WITHOUT INCIDENT. LEFT PRESS RELIEVE VALVE OBSERVED EXTENDED DURING POST FLIGHT. REPLACED LEFT COWL ANTI-ICE VALVE AND RESET LEFT ENGINE PRESS RELIEVE VALVE. NO FURTHER DEFECTS.