BoilerFaultCodes Connection
No communication between the PCB and the user interface
Glow-worm SUSTAIN 30c Fault codes & diagnostics
41 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Gas 2015-present
GC Number 47-019-33
Download the Glow-worm SUSTAIN 30c manual
PDF
Versions & GC numbers
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 41 Unrated
Which version do you have?
The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 47-019-33 | SUSTAIN 30c | 2015–present |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
Just want the most common Glow-worm SUSTAIN 30c faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 41 documented codes
Tap any card for details
F.00
Fault: Flow temperature sensor
F.01
Fault: Return temperature sensor
F.10
Short circuit: Flow temperature sensor
F.11
Short circuit: Return temperature sensor
F.12 and F.91
Short circuit: Cylinder temperature sensor
F.13
Short circuit: Domestic hot water cylinder temperature sensor
F.20
Safety switch-off: Overheating temperature reached
F.22
System water pressure too low (switches off the product)
F.23
Safety switch-off: Temperature difference too great (NTC1/NTC2)
Showing 11–20 of 41
F.24
Safety switch-off: Temperature rise too fast
F.25
Safety switch-off: Flue gas temperature too high
F.27
Safety switch-off: Fault in flame detection
F.28
Fault: Ignition unsuccessful when starting up
F.29
Fault: Flame loss
F.32
Fan frost protection function active: Fan speed outside the tolerance values
F.33
Fan frost protection function active: Air pressure switch fault
F.49
eBUS fault: Voltage too low
F.61
Fault: Gas valve control system
F.62
Fault: Gas valve switch-off control
Showing 21–30 of 41
F.63
Fault: EEPROM
F.64
Fault: Electronics/sensor/analogue-to-digital converter
F.65
Fault: Electronics temperature too high
F.67
Value sent back by ASIC is incorrect (flame signal)
F.68
Fault: Unstable flame (analogue input)
F.70
Invalid product code (DSN)
F.71
Fault: Flow/return temperature sensor
F.72
Fault: Deviation in the water pressure sensor/return temperature sensor
F.73
Fault: Water pressure sensor not connected or has short-circuited
F.74
Fault: Electrical problem in the water pressure sensor
Showing 31–40 of 41
F.75
Fault: Pressure sensor
F.76
The safety cut-out in the primary heat exchanger is defective
F.77
Fault: Condensate or smoke
F.78
Interruption to DHW outlet sensor at external controller
F.83
Fault: Burner temperature sensor
F.84
Fault: Flow/return temperature sensor
F.85
Fault: Temperature sensor
F.86
Fault: Underfloor heating contact
F.87
Fault: Electrodes
F.88
Fault: Gas valve
Showing 41–41 of 41
F.89
Fault: Pump
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