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
displayed
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.
5
4
4
3
2
0
7
v
1
.5