Code Faults
Cause
of the
fault
Description
Checking / solution
L32
DEF.OUTLET S.
PCU
The boiler flow sensor has short-
circuited
Bad connection
4
Check the wiring between the PCU PCB and the
sensor
4
Check that the SU PCB is correctly in place
4
Check that the sensor has been correctly fitted
Sensor fault
4
Check the Ohmic value of the sensor
4
Replace the sensor if necessary
L33
DEF.OUTLET S.
PCU
The boiler flow sensor is on an
open circuit
Bad connection
4
Check the wiring between the PCU PCB and the
sensor
4
Check that the SU PCB is correctly in place
4
Check that the sensor has been correctly fitted
Sensor fault
4
Check the Ohmic value of the sensor
4
Replace the sensor if necessary
L34
FAN FAILURE
PCU
The fan is not running at the right
speed
Bad connection
4
Check the wiring between the PCU PCB and the
fan
Fan defective
4
Check for adequate draw on the chimney
connection
4
Replace the fan if need be
L35
BACK>BOIL FAIL
PCU
Flow and return reversed
Bad connection
4
Check that the sensor has been correctly fitted
Sensor fault
4
Check the Ohmic value of the sensors
4
Replace the sensor if necessary
Water circulation direction reversed
4
Check the circulation (direction, pump, valves)
L36
I-CURRENT FAIL
PCU
The flame went out more than 5
times in 24 hours while the burner
was operating
No ionization current
4
Purge the gas supply to remove air
4
Check that the gas valve is fully opened
4
Checking the gas supply pressure
4
Check the operation and setting of the gas valve
unit
4
Check that the air inlet and flue gas discharge
flues are not blocked
4
Check that there is no recirculation of flue gases
L37
SU COM.FAIL
PCU
Communication failure with the
SU PCB
Bad connection
4
Check whether the SU PCB has been correctly
fitted into the connector on the PCU PCB
4
Change the SU PCB
Diematic iSystem For C 330 / C 630 ECO
7. Troubleshooting
31082018 - 7600691-001-06
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