As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SITTING ON THE RAMP IDLING, RECEIVED A HIGH CO2 WARNING AFTER A COUPLE ON MINUTES. SHUTDOWN ENGINE AND CO2 WARNING CEASED. INSPECTED MUFFLER AND FOUND SPOT WELDS PULLING OUT FROM MUFFLER LINER THEREFORE RELEASING EXHAUST INTO HEAT SHROUD.