Fault finding and diagnosis
Greenstar 4000 – 6 720 891 162 (2020/09)
76
2916 V
Boiler electr. system fault
Gas valve was detected as open during post-purge.
▶ Carry out a gas tightness test on the gas valve and replace if required.
▶ Check the voltage to gas valve.
▶ The gas valve or the PCB may be defective
2920 V
Fault in flame monitoring
▶ Check electrodes and connecting leads, replace if required.
▶ Check protective earth conductor connections (PE).
▶ Check appliance electronics, replace control unit if necessary.
2923 V
Boiler electr. system fault
Unexpected feedback from the modulating/current controlled gas valve.
▶ Check the voltage to the gas valve.
▶ Check the continuity of harness and replace if required.
▶ Check the resistance of the gas valve coils.
▶ The gas valve or the appliance electronics (control unit) may have a fault.
2927 B
Boiler electr. system fault
No ionisation detected after ignition.
▶ Check the main shut-off valve, open if necessary.
▶ Check the appliance isolation valve, open if necessary.
▶ Measure the gas supply pressure at the rated heat input. If necessary, shut down the
appliance and check the gas line.
▶ Check flame sense electrode and connecting lead, replace if required.
▶ Check venturi/injector for potential blockage.
▶ Measure the ionisation current.
▶ Check the protective earth conductor connection (PE) in the control unit.
▶ Check the ignition cable for damage, replace if necessary.
▶ Check functionality of gas valve and replace if necessary.
▶ Check CO
2
settings at min and max output
▶ Check flue system.
▶ Check combustion air supply.
▶ Check the heat exchanger on the flue gas side for deposits, clean if necessary.
2928 V
Internal fault
▶ Restart appliance.
▶ If the fault persists following a reset, the burner control unit is faulty and must be
replaced, (replace control unit).
2931 V
System fault boiler electronics / basic
controller
Illegal instruction.
▶ Restart appliance.
▶ If the fault persists following a reset, the burner control unit is faulty and must be
replaced, (replace control unit).
2940 V
System fault burner control unit
Low voltage.
▶ Restart appliance.
▶ If the fault persists following a reset, the burner control unit is faulty and must be
replaced, (replace control unit).
2946 V
Incorrect code plug detected
▶ Check code plug, replace if necessary.
2948 B
No flame signal with low output
Burner starts automatically after purging. This can be caused by strong winds.
If this fault occurs frequently:
▶ Check CO
2
settings.
▶ Check flue outlet position for effects of excessive wind pressure.
▶ Check flue integrity.
2949 B
No flame signal with high output
May be caused by strong winds or flue gas recirculation. The burner starts automatically
after purging.
▶ Check the flue integrity.
▶ Check the flue terminal position.
▶ Check the CO
2
settings and adjust if necessary.
▶ Check the burner and the heat exchanger gaskets and the inner flue gaskets.
▶ Check the gas pressure during burning at full load (working pressure, dropping low).
2950 B
No flame signal following starting procedure ▶ Check gas pressure whilst burning at full load.
▶ Check CO
2
settings, adjust if necessary.
▶ Check Burner and heat exchanger gaskets.
▶ Burner restarts automatically after purging.
Fa
ult
co
de
Fa
ult
ca
te
go
ry Fault text on the display, description
Remedy
