Fault finding and diagnosis
71
Greenstar 4000 – 6 720 891 161 (2020/09)
10.1.2 Operating/Fault code table
Fault
code
Fault
category
Fault text on the display, description Remedy
200 O Boiler in heating mode Operating message, is not a fault.
• Heating circuit is being heated.
201 O Boiler in hot water mode Operating message, is not a fault.
• Hot water circuit is being heated.
202 O Boiler in anti-cycle mode Operating message, is not a fault.
• Anti-cycle mode - this is the standby time between heating demands - default 5
minutes.
– For example, if there is heating demand for 1 minute, the boiler will wait for 4
minutes after the heating demand before firing for a subsequent heating demand.
Fault code 202 will be present during anti-cycle mode.
203 O Boiler in standby, no heat energy demand Operating message, is not a fault.
• Appliance in standby, awaiting a demand request.
204 O Current prim. water temp. higher than set
val.
Operating message, is not a fault.
• System waiting. The actual boiler water temperature is higher than the target boiler
water temperature. The boiler heat demand is switched off.
208 O Chimney sweep demand Operating message, is not a fault.
• Chimney sweep mode active.
214 V Fan shut down during safety time ▶ Reset the appliance.
▶ Create a heat demand; check if the boiler fires up.
▶ Check the voltage to the fan and the continuity of the fan harness.
▶ Check the power modulation on the fan.
▶ PCB may be defective.
224
224
B
V
Maximal flue gas thermostat or heat
exchanger maximal thermostat has
activated
Maximal flue gas thermostat or heat
exchanger maximal thermostat has
activated
If the blocking fault persists for a prolonged period, it becomes a locking fault.
▶ Check if the lead is disconnected from the safety temperature limiter/thermostat or
the flue thermostat.
▶ Check the high limit of the safety temperature limiter/thermostat or the flue
thermostat and the harness for continuity.
▶ Check the flow temperature to confirm actual temperature (may have tripped out at
lower temperature, leading to a safety temperature limiter/thermostat or the flue
thermostat fault).
▶ Check the system pressure and top up as required.
▶ Check if air is trapped in the system and in the boiler.
▶ Pump seized/not running: check the pump for failure or blockage.
▶ Check if a blockage/restriction within boiler/pipework is restricting the flow.
227 V No flame signal after ignition Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist
and pull the ceramic insulator to ensure it is not broken.
▶ Check the gas supply to the property and the inlet on the gas valve.
▶ Check for low pressure when the gas valve opens.
▶ Gas valve failing to open: check for voltage to the valve and for possible blockage on
inlet filter of the gas valve.
▶ Obstruction in the air intake to the fan leading to incorrect CO
2
ratio.
▶ Condensate siphon is blocked or restricted. Condensate pipe is frozen.
▶ Flue is blocked or restricted.
▶ Heat exchanger is blocked or restricted.
▶ Check the burner for damage.
▶ Check the spark electrode/lead for failure.
▶ Check the flame sense/lead for failure.
▶ Check the rectification ground (black wire to heat exchanger).
228 V Flame signal without flame present Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist
and pull the ceramic insulator to ensure it is not broken.
▶ Check the flame sense and the lead and replace if required.
▶ Check the earth tags on the boiler and on the electrodes.
▶ Check the operation of the siphon and that no water is collecting in the sump.
▶ Replace the gas valve.
▶ Replace the control unit and/or burner control unit.
232 B Boiler locked by external switching contact External cut off switch not used in UK:
▶ Ensure nothing is plugged into red I3 connection.
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