As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE FROM SAT TO OKC, THE CREW RECEIVED A LEFT HAND HIGH PRESSURE FILTER BYPASS CAS MESSAGE AND RETURNED TO SAT. FAIRCHILD MAINTENANCE INSPECTED AND REPLACED THE HIGH PRESSURE FILTER AND THE HIGH PRESSURE BYPASS TEMPERATURE SENSOR IN ACCORDANCE WITH DORNIER MAINTENANCE MANUAL 73-00-00. OPERATIONAL TESTS WERE PERFORMED AND THE AIRCRAFT WAS RELEASED FOR SERVICE.