"Probe heat computer
Some of the PFR messages indicated a potential fault with the number-1 probe heat computer (PHC). Those messages could be generated by either a PHC fault or by an ADIRU fault. The PHC (serial number 2083) was tested by an authorised agency and no fault was found. Based on a review of available information, the messages related to the PHC were considered to be spurious."
http://www.atsb.gov.au/publications/...70_interim.pdf