Faults
Code Cause
of the
error
Description
Checking / solution
PARASIT FLAME
L16
PCU
Detection of a parasite flame
Ionisation current present when there should not be a
flame
Ignition transformer defective
4
Check the ionisation/ignition electrode
Gas valve defective
4
Check the gas valve and replace if necessary
The burner remains very hot: CO
2
too high
4
Set the CO
2
VALVE FAIL
L17
PCU
Problem on the gas valve
Bad connection
4
Check the wiring between the PCU PCB and the
gas valve
4
Check that the SU PCB is correctly in place
SU PCB faulty
4
Inspect the SU PCB and replace it if need be
FAN FAILURE
L34
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
BACK>BOIL FAIL
L35
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)
I-CURRENT FAIL
L36
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
SU COM.FAIL
L37
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
PCU COM.FAIL
L38
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
MCA 15 - MCA 25 MCA 25/28 MI
8. Troubleshooting
29/04/2010 - 300022146-001-B
119
