As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT A STRONG EXHAUST ODOR EMITTED FROM THE PILOTS OVERHEAD WEMAC. COPILOTS SIDE UNAFFECTED. RAN APU AND CHECKED CABIN AND COCKPIT TEMP CONTROL. SYSTEM FUNCTIONAL. DIDN'T DETECT ANY EXHAUST COMING FROM WEMACS. OPS CHECK GOOD. WORK PERFORMED IAW MM CHAPTER 21-51-00 21-61-00.