As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE DTW-YHZ, AIRFOIL ICE PROTECTION PRESSURE ABNORMAL LIGHT REMAINED ON DURING WING ANTI-ICE OPERATION. FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. REPLACED THE TAIL ANTI-ICE VALVE, NO HELP. REPLACED THE PRESSURE SWITCH AND OPERATIONAL CHECK NORMAL. AIRCRAFT RETURNED TO SERVICE.