TQ FC00 - heater has recovered from a fault, but the lockout state on the ICS PCB did not update.
May happen when there is a power outage causing a glitch. If unable to reset on MagIQtouch use the reset button on the ICS PCB.
NB: This is a rare intermittent issue and there is no need to change ICS PCB for a FC00
TQ DGH - FAULT RESET Button Location on ICS PCB - next to gas valve plug (yellow black and orange wires)
Fault code history can be accessed:
SETTINGS/SERVICE/GAS HEATER 01/7378 CONT/FAULT LOG