As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT DURING FLIGHT WHEN ENGINE ANTI-ICE WAS SELECTED ON AND WHEN TURNED OFF THE LEFT ENGINE ANTI-ICE INDICATION WOULD REMAIN ON FOR AN ADDITIONAL 20 MINUTES BEFORE EXTINGUISHING. THE MAINTENANCE VENDOR TROUBLESHOT AND DETERMINED THE LEFT ENGINE TEMPERATURE SWITCH/SENSOR WAS DEFECTIVE AND WAS REPLACED WITH A NEW UNIT. OPS CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.