Fault Finding - Worcester Greenstar Highflow 440CDi ERP Installation, Commissioning And Servicing Instructions

7.5

Fault finding

▶ 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).
BOILER - FAULTS AND CONDITIONS
Display
code: Fault description
A1 Pump dry run detection
or
Pump is running in air
A5 Tank NTC defect
A7 DHW NTC defect
A8 EMS communication error
b1 Code plug not detected
b2, b3, b4, Data error
b5,b6
b7 Burner control error
C6 Fan defect
d3 External temp limiter
d5 Condensate pump failure
d6 Internal heat bank overflow
EA Flame not detected
E2 Primary NTC defect
E9 OH stat tripped
F0 Internal error
F1 ROM error check
F7 Flame detected after appliance shut off
FA Flame detected after gas shut off
Fd Reset button pressed
Table 17
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.
6720818077 (2016/04) -
Greenstar Highflow CDi
Check, repair/replace as necessary
Check the system pressure, refill if necessary
Check tank NTC sensor and leads, measure resistance across NTC (33.5k Ω- 500 Ω)
Check DHW NTC sensor and leads, measure resistance across NTC (33.5k Ω- 500 Ω)
Check electrical connections of EMS controls (if fitted), connections on the control board,
replace control board.
Insert code plug correctly, test and replace as necessary.
Replace control board.
Replace control board.
Check fan, lead, and connector, replace as necessary.
Check plug connector ST8, link missing/damaged between 8 & 9 on ST8.
See condensate pump table.
Check system pressure, tank overheat thermostat and leads, and pump operation
Check gas is present and working gas pressure, ignition electrodes and harness, flame sense
electrode and harness, and operation of gas valve. Replace as necessary.
Check primary NTC sensor and leads, resistance across NTC should be between 36k to 1k Ω
Check system pressure, over heat thermostat, and pump operation.
Check fuse (T1.6A slow blow), replace as necessary.
Check all electrical connections, replace control board as necessary.
Check all electrical connections, replace control board as necessary.
Check flame sense electrode and harness, and control board for signs of water damage.
Replace as necessary
Check flame sense electrode and harness, and control board for signs of water damage.
Check gas valve operation. Replace as necessary
Press reset button again
ErP
FAULT FINDING AND DIAGRAMS
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