BoilerFaultCodes 20
Central Heating NTC Fault
Baxi Duo-tec 2 Combi 28 Compact Fault codes & diagnostics
17 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 2013-2015 Discontinued
GC Number 47-075-72
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Severity at a glance
Each cell = one fault code. Hover to identify. 17 Unrated
Just want the most common Baxi Duo-tec 2 Combi 28 Compact faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 17 documented codes
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28
Flue NTC Fault
40
Central Heating Return NTC Fault
110 R
Safety Thermostat Operated (pump fault or air in primary)
111 R
Safety Thermostat Operated (over temperature)
117
Primary System Water Pressure Too High
118
As pressure reduces Error Code 118 will begin to flash. Once the pressure is less than 0.5 bar the boiler will not operate & 118 will be displayed constantly
125 R
Circulation Fault (Primary)
128
Flame Failure (no lock-out)
130
Flue NTC Operated
133 R
Interruption Of Gas Supply or Flame Failure
151 R
Flame Failure
160 R
Fan or Fan Wiring Fault
321
Hot Water NTC Fault
384
False Flame
E117
system pressure exceeds 3 bar, safety pressure valve will operate
E118
system pressure low, requires repressurising