BoilerFaultCodes FAN LOCKOUT
Unplug 3-way PCB connector & unplug fan. Unplug the smaller of the 6-way PCB connector.
Main 12 Heat ErP Fault codes & diagnostics
4 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Gas 2006-present
GC Numbers 41-467-2341-467-2441-467-2541-467-26
Download the Main 12 Heat ErP 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 →
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 |
|---|---|---|
| 41-467-23 | 12 Heat ErP | 2006–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 Main 12 Heat ErP faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 4 documented codes
Tap any card for details
IGNITION LOCKOUT
Is there gas at gas valve inlet? Is there gas flow from gas valve? Is there at least 18mbar dynamic at gas valve inlet?
OVERHEAT LOCKOUT
Disconnect black stat on flow pipe. Disconnect fan stat. Disconnect the larger of the 6-way PCB connectors. Disconnect thermistor.
THERMISTOR
Unplug thermistor, check resistance between 0.5kΩ & 20kΩ
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