FAULT FINDING AND DIAGRAMS
6720818077 (2016/04) - Greenstar Highflow CDi
ErP
47
7.5 Fault finding
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.
▶ 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 Check, repair/replace as necessary
A1 Pump dry run detection
or
Pump is running in air
Check the system pressure, refill if necessary
A5 Tank NTC defect Check tank NTC sensor and leads, measure resistance across NTC (33.5k Ω- 500 Ω)
A7 DHW NTC defect Check DHW NTC sensor and leads, measure resistance across NTC (33.5k Ω- 500 Ω)
A8 EMS communication error Check electrical connections of EMS controls (if fitted), connections on the control board,
replace control board.
b1 Code plug not detected Insert code plug correctly, test and replace as necessary.
b2, b3, b4,
b5,b6
Data error Replace control board.
b7 Burner control error Replace control board.
C6 Fan defect Check fan, lead, and connector, replace as necessary.
d3 External temp limiter Check plug connector ST8, link missing/damaged between 8 & 9 on ST8.
d5 Condensate pump failure See condensate pump table.
d6 Internal heat bank overflow Check system pressure, tank overheat thermostat and leads, and pump operation
EA Flame not detected 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.
E2 Primary NTC defect Check primary NTC sensor and leads, resistance across NTC should be between 36k to 1k Ω
E9 OH stat tripped Check system pressure, over heat thermostat, and pump operation.
Check fuse (T1.6A slow blow), replace as necessary.
F0 Internal error Check all electrical connections, replace control board as necessary.
F1 ROM error check Check all electrical connections, replace control board as necessary.
F7 Flame detected after appliance shut off Check flame sense electrode and harness, and control board for signs of water damage.
Replace as necessary
FA Flame detected after gas shut off Check flame sense electrode and harness, and control board for signs of water damage.
Check gas valve operation. Replace as necessary
Fd Reset button pressed Press reset button again
Table 17
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