Technical data

Troubleshooting
59
Diagnostics (continued)
Fault codes (continued)
Fault code on display System behavior
*1
Cause Corrective action
F2 Burner in fault mode Fixed high limit switch
open (activated)
Check heating system fill
level. Check the circulation pump.
Bleed air from the system. Check fixed
high limit switch and connecting cables.
Press ” RESET”
F3 Burner in fault mode Flame signal already
present at burner start
Check the ionization
electrode and connecting cable.
Press ” RESET”
F4 Burner in fault mode No flame signal Check the ionization electrode and
cable, measure the ionization current,
check the gas pressure, check the gas
valve, ignition, ignition module, ignition
electrodes and the condensate drain.
Press ” RESET”
F8 Burner in fault mode Gas valve closes too late Check the gas valve. Check both control
wiring/connections. Press RESET.
F9 Burner in fault mode Fan speed too low during
burner start
Check the fan, the fan cables and
power supply. Check the fan control.
Press RESET
FA Burner in fault mode Fan not at standstill Check the fan, the fan connecting
cables and fan control. Check the fan
control. Press ” RESET”
FC Burner in fault mode Gas valve faulty or faulty
modulation valve control;
or vent system blocked
Check the gas valve. Check the vent
system.
Press ” RESET”
Fd Burner in fault mode Burner control unit fault Check ignition electrodes and
connecting cables. Check whether a
strong interference (EMC) field exists
near the equipment. Press RESET.
Replace control unit if fault persists
FE Burner blocked or in
fault mode
Strong interference (EMC)
field nearby or faulty main
PCB.
Restart the equipment.
Replace the control unit if the
equipment will not restart
FF Burner blocked or in
fault mode
Strong interference (EMC)
field nearby or faulty main
PCB.
Restart the equipment.
Replace the control unit if the
equipment will not restart
No fault code dis-
played
Boiler/burner in
standstill
Flow switch open Check pump operation and flow switch
*1
Control mode: Boiler/burner fully operational (fault code must be verified and reset).
Burner in fault mode: Boiler control requires manual reset before burner can resume operation.
Burner blocked: If fault cause is corrected, burner resumes operation.
5418 911 v1.6