Faults
Greenstar – 6721822579 (2021/01)
74
17.2
Faults that are shown on the display
Display
Description
Elimination
A7
DHW temperature sensor defective.
▶ Check temperature sensor and leads for interruptions or shorts, and
replace if defective.
▶ Insert code plug correctly; replace if defective.
A8
Communication fault.
▶ Check BUS communications wiring, replace if defective.
▶ Check control, replace if defective.
Ad
DHW tank temperature not detected.
The DHW tank temperature sensor was recognized
before the connection was lost.
▶ Check DHW tank temperature sensor and connecting lead, replace if
defective.
▶ Reset the boiler to the factory default settings (
service function 8.E).
b1
Code plug not detected.
▶ Insert code plug correctly; replace if defective.
b2/b3/b4/
b5/b6
Internal data error.
▶ Reset boiler to the factory default setting (
service function 8.E).
b7
Fault in the burner controls.
▶ Reset boiler to factory to default setting ( service function 8.E).
C6
Fan not running.
▶ Check fan leads and fan, replace if defective.
CC
Outdoor temperature sensor not recognized.
▶ Check outdoor temperature sensor and leads for interruptions, replace if
defective.
▶ Verify the outdoor temperature sensor is connected to terminals A and F.
d3
Temperature high limit defective.
External guard has tripped.
Temperature limiter locked out.
▶ Check temperature sensor and leads for interruptions or shorts, and
replace if defective.
▶ Temperature guard TB1 has tripped. Check if jumper across 8-9 or PR-P0
is missing.
▶ Reset external temperature limiter (if installed).Reset LWCO (if installed).
▶ Reset pressure regulator (if installed).
d5
External supply temperature sensor defective (low-loss
header).
The external supply temperature sensor was recognized
on the BUS and then reconnected to the appropriate
terminal.
▶ Check temperature sensor and leads for interruptions or shorts, and
replace if defective.
▶ Check whether only one temperature sensor is connected; otherwise
remove second temperature sensor.
▶ Reset the boiler to the factory default settings (
service function 8.E).
E2
Supply temperature sensor defective.
▶ Check temperature sensor and leads for interruptions or shorts, and
replace if defective.
E3
Additional supply temperature sensor defective.
▶ Check temperature sensor and leads for interruptions or shorts, and
replace if defective.
E9
Heat exchanger safety high limit or flue gas temperature
limiter has tripped.
▶ Check flue gas safety high limit and leads for interruptions or shorts, and
replace if defective.
▶ Check heat exchanger safety high limit and leads for interruptions or shorts,
and replace if defective.
▶ Check the operating pressure.
▶ Check temperature limit; replace if defective.
▶ Check pump capacitor; replace pump if defective.
▶ Check PCB fuse, replace if blown (6.3 A fuse according to IEC default).
▶ Purge the appliance.
▶ Check heat exchanger on the DHW side; replace if clogged.