FAULT FINDING
& DIAGRAMS
INSTALLATION & SERVICING INSTRUCTIONS
52
FAULT FINDING
8 716 115 219b (09.2008)
NOTE ; This fault finding information is for
guidance only. Worcester Bosch cannot be held
responsible for costs incurred by persons not
deemed to be competent.
The electronic control system for this boiler
incorporates a blue central indicator. This
normally confirms the permanent mains supply,
but, by flashing during a fault, provides a guide
to the cause as listed.
This fault finding system assumes that the
appliance has been operating normally until the
time of failure (i.e. not a first time installation
error).
Preliminary checks:
Preliminary electrical system checks are the
first electrical checks to be carried out during
a fault finding procedure.
On completion of the Service/Fault finding
task which has required the breaking and
remaking of electrical connections, check:
a) EARTH CONTINUITY
b) SHORT CIRCUIT CHECK
c) POLARITY
d) RESISTANCE TO EARTH.
FAULT FINDING
Check, repair/replace as necessary:
check tank NTC and leads
check hot water NTC and connecting lead
check electrical connections.
Insert code plug correctly.
software/pcb error.
software/pcb error.
check fan, lead and connector.
check external stat.
check condensate pump and leads.
check tank overheat thermostat
check gas supply and igniter electrode.
check CH NTC and lead.
check system pressure and pump.
check electrical connector contacts.
software/pcb error.
check electrode assembly, dry pcb.
check gas valve and leads.
press reset button again.
Display
Code:
A5
A7
A8
b1
b2, b3, b4
b5, b6
b7
C6
D3
D5
D6
EA
E2
E9
F0
F1
F7
FA
Fd
Fault description:
Tank NTC defect
DHW NTC defect
EMS coms error
Code plug not detected
Data error
Burner control error
Fan defect
External Temp limiter
Condensate overflow
Internal heatbank overheated
Burner control lockout
Primary NTC defect
OH stat tripped
Internal error
Rom check error
Flame detected after
apliance shut off
Flame detected after gas
shut off
Reset button pressed
BOILER - FAULT CODES AND CONDITIONS
CONDENSATE PUMP - OPERATING LAMPS AND FAULT CONDITIONS
Ready for operation = Steady green light
Fault = Red light
Pump running = Flashing green light
Operating lamps Cause Solution
Green Red
Off Off Mains plug not plugged in Insert plug
Power failure Check mains and fuse
Flashing Flashing Dry-run Pump restarts automatically
(poss. air in pump) after one minute
On Flashing Pump blocked Visual inspection of the pump inlet
in the tank and removal or
rinsing out of dirt/foreign bodies
On On Level exceeds alarm level Pressure hose / non-return valve
blocked (clean or remove kink
if applicable)
Off Flashing Pump blocked and Visual inspection of the pump inlet
alarm level exceeded in the tank and removal or
rinsing out of dirt/foreign bodies
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