2001 3.8 mustang error code OBDII P1285

Can anyone tell me what is causing this code to come up.. i know it means cylinder head over temp sensed. this code came up a couple weeks ago and recently i had replaced the head gaskets & all the other gaskets that needed to be rreplaced during the job.

i have already checked the obvious like coolant fluid level, thermostat, etc.


Can anyone give me actual details of this code, the possible causes, repair procedures for the issue throwing this code>???