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Code Faults
Cause
of the
fault
Description
Checking / solution
L31
DEF.SMOKE.TEMP
PCU
The maximal smoked
temperature is exceeded of 5
times in 24 hours.
4
Check the level of fouling of the heating body
4
Check the burner setting and the take
combustion measurements
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 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 sensor has been correctly fitted
Sensor fault
4
Check the Ohmic value of the sensor
4
Replace the sensor if necessary
L34
BACK S.FAILURE
PCU
The return temperature sensor
has short-circuited
Bad connection
4
Check the wiring between the PCU PCB and the
sensor
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
L35
BACK S.FAILURE
PCU
The return temperature sensor
is on an open circuit
Bad connection
4
Check the wiring between the PCU PCB and the
sensor
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
L36
DEF.FLAME LOS
PCU
3 flame losses during a heating
demand
No flame signal
4
Air present in the oil circuit
4
Check that the oil valve is actually open
4
Check that the flame detection cell is in good
condition
4
Check that there is no recirculation of flue gases
L37
SU COM.FAIL
PCU
Communication breakdown
with the safety box
Bad connection
4
Check whether the SU PCB has been correctly
fitted into the connector on the PCU PCB
4
Change the safety control box and then reset the
box
L38
PCU COM.FAIL
PCU
Communication failure
between the PCU and SCU
PCBs
Bad connection
4
Check the wiring between the PCU and SCU
PCBs
4
Run an
AUTODETECTION
in the menu
#CONFIGURATION
SCU PCB not connected or faulty
4
Replace the SCU PCB
AFC 18 - AFC 24 - AFC 30
9. Troubleshooting
09/07/2015 - 300026439-07
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