BoilerFaultCodes DU
Diverter valve actuator step
Ideal CLASSIC2 Fault codes & diagnostics
26 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Gas 2019-present
GC Numbers 47-349-7147-349-7247-349-73
Download the Ideal CLASSIC2 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. 26 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 |
|---|---|---|
| 47-349-71 | CLASSIC2 24 | 2019–present |
| 47-349-72 | CLASSIC2 30 | 2019–present |
| 47-349-73 | CLASSIC2 35 | 2019–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 Ideal CLASSIC2 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 26 documented codes
Tap any card for details
F[-]
Boiler has a fault for a specific error
F1
Low Water Pressure
F2 Or Fn Or Ln
Flame Loss
F3
Fan Fault
F6
Outside Sesnor Fault
F7
Low Mains Voltage
F8 or L8
PCB UNCONFIGURED/FAULTY OR GAS VALVE SHORT CIRCUIT
F8/L8
Lockout Due To Parameter Fault
F9
PCB programming mode
Showing 11–20 of 26
F9 or L9
REPLACE PCB
F9/L9
PCB Fault
FA
NEGATIVE DIFFERENTIAL FLOW OR RETURN THERMISTOR FAULT
FU
DIFF GREATER THAN 50°C
L[-]
Boiler is in lockout for a specific error
L1
Flow Temperature Overheat Lockout
L2
Boiler ignition failure
L4 Or F4
Flow Thermistor Fault
L5 Or F5
Return Thermistor Fault
L6
False Flame Lockout
Showing 21–26 of 26
LC
Boiler lockout after 5 reset attempts within 15 minutes
oF
PCB programming mode
SH
Diverter valve actuator step
SL
Status code shown after the last 3 faults are displayed
UF
Diverter valve actuator step
uP
PCB programming mode
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