Fault finding and diagnosis
Greenstar 4000 – 6 720 891 161 (2020/09)
78
Table 31 Indicators and fault displays
2971 B System pressure too low System pressure is very or extremely low. This is triggered when the pressure falls to
between 0.6 and 0.3 bar. Top up water until the target pressure is reached.
Intelligent filling loop
▶ Check in Main menu if Start filling option is available and select Yes option to start
filling.
▶If Start filling option not available, switch off the automatic filling function (Autom.
filling > No) in the system menu, re-pressurise manually and vent the system.
▶ Ensure the correct pressure then factory reset appliance. If cause code does not clear,
power off appliance.
Other filling loop
▶ Vent the heating system and top up water until the target pressure is reached.
Pressure sensor
▶ Check the continuity down harness for the pressure sensor and replace if required.
▶ Check the voltage at the pressure sensor and replace if required.
2972 V Mains voltage too low ▶ Establish supply voltage of at least 196 VAC.
▶ Replace control unit.
3071 – Comfort + II RF
▶ Check the configuration (address setting). The selected setting requires a hard-wired
room control.
▶ Check the EMS connection cable of the room control for damage. The BUS voltage on
the room control must be between 12 and 15 V DC.
▶ Disconnect the EMS-BUS connection to the control unit and power the boiler off and
back on again. Reconnect the EMS-BUS connection.
▶ If the problem persists the room control may be defective.
Fault
code
Fault
category
Fault text on the display, description Remedy
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