As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, PILOT NOTICED A BURN ODOR IN COCKPIT. PILOT THEN NOTED THAT DOOR POST TRIM PANEL WAS DISCOLORED. RETURNED TO AIRPORT AND NOTIFIED MECHANIC. MECHANIC FOUND THE PRESSURE REGULATOR TO BE FAULTY. FURTHER INVESTIGATION LED TO REPLACEMENT OF THE PRESSURE RELIEF VALVE AND ALL THREE DEICE SOLENOIDS (PRECAUTIONARY MEASURE). PERFORMED MECHANIC FLIGHT AFTER, NO FURTHER DEFECTS NOTED.