BoilerFaultCodes
Protherm Boiler Fault Codes
25 fault codes across 2 Protherm boiler models — explained in plain English.
Protherm (Vaillant Group) domestic boilers.
Protherm fault codes on this site
We document 25 fault codes across 2 Protherm models, covering 23 distinct codes. Protherm boilers use letter-and-number codes such as F0, F1, F2. Codes for 2 of these models are taken directly from the manufacturer's own service or installation manual. Protherm is a smaller name in the UK market, and if you own one this is likely one of the few places its fault codes are collected in one place.
Models covered: 100EC, 40-50 CI.
Just want the most common Protherm problems?
The top 8 faults across the whole Protherm range — causes, DIY checks, repair costs.
High-severity Protherm fault codes
F0 F1 F2 F3 n4
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
100EC
Your boiler has failed to light or has lost its flame, so it has shut down for safety purposes.
100EC
Your boiler has stopped working because it cannot correctly measure the temperature of the water inside the pipes.
100EC
Your boiler is unable to circulate water properly through its internal heating system, causing it to shut down for safety.
100EC
Your boiler has identified a communication failure between the control panel and the main heating system, preventing it from operating correctly.
100EC
All models
2 Protherm boiler models
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