DE DIETRICH AFC 18 - AFC 24 - AFC 30 - Manual (Page 36)

Code Faults Cause
of the
fault Description Checking / solution
L30 DEF.FLUE GAS
PRESSURE PCU The flue gas pressure switch
opened 5 times in 24 hours.
4 Contact the professional who takes care of
maintenance of the appliance
L31 DEF.SMOKE.TEMP PCU The maximal smoked temperature
is exceeded of 5 times in 24 hours.
4
Contact the professional who takes care of
maintenance of the appliance
L32 DEF.OUTLET S. PCU The boiler flow sensor has short-
circuited
Bad connection
Sensor fault
4 Contact the professional who takes care of
maintenance of the appliance
L33 DEF.OUTLET S. PCU The boiler flow sensor is on an open
circuit
Bad connection
Sensor fault
4
Contact the professional who takes care of
maintenance of the appliance
L34 BACK S.FAILURE PCU The return temperature sensor has
short-circuited
Bad connection
Sensor fault
4
Contact the professional who takes care of
maintenance of the appliance
L35 BACK S.FAILURE PCU The return temperature sensor is
on an open circuit
Bad connection
Sensor fault
4 Contact the professional who takes care of
maintenance of the appliance
L36 DEF.FLAME LOS PCU 3 flame losses during a heating
demand
4 Contact the professional who takes care of
maintenance of the appliance
L37 SU COM.FAIL PCU Communication breakdown with
the safety box
Bad connection
4
Contact the professional who takes care of
maintenance of the appliance
L38 PCU COM.FAIL PCU Communication failure between the
PCU and SCU PCBs
Bad connection
SCU PCB not connected or faulty
4 Contact the professional who takes care of
maintenance of the appliance
L39 BL OPEN FAIL PCU The BL inlet opened for a short time Bad connection
External cause
Parameter incorrectly set
4
Contact the professional who takes care of
maintenance of the appliance
L250 DEF.WATER MIS. PCU The water pressure is too low Hydraulic circuit incorrectly vented
Water leak
Measurement error
4 Top up with more water if necessary
4 Reset the boiler
L251 MANOMETRE FAIL PCU Fault on the water pressure sensor Wiring problem
Failure water pressure switch
Sensor pcb defect
4
Contact the professional who takes care of
maintenance of the appliance
D03
D04 OUTL S.B FAIL.
OUTL S.C FAIL. SCU Circuit B flow sensor fault
Circuit C flow sensor fault
Remarks:
The circuit pump is running.
The 3-way valve motor on the
circuit is no longer powered and can
be adjusted manually.
Bad connection
Sensor fault
4 Contact the professional who takes care of
maintenance of the appliance
6. Troubleshooting AFC 18 - AFC 24 - AFC 30
35 09/01/2014 - 300026440-001-03