As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED THAT THE INSTRUMENT PANEL MOUNTED, PASSIVE-TYPE, CARBON MONOXIDE INDICATOR DISK TURNED BLACK WHILE EN ROUTE AND TEN MINUTES FROM LANDING. MAINTENANCE HAS NOT LOOKED INTO THE PROBLEM AT THE TIME THAT THIS REPORT IS BEING GENERATED. INSPECTED EXHAUST SYSTEM AND FOUND NO LEAKS. REPLACED CO INDICATOR AND TEST FLEW SATISFACTORY. (M)