BoilerFaultCodes 76
ALTERNATING ‘F’ AND ‘7’ - LOW MAINS VOLTAGE
Ideal Classic Fault codes & diagnostics
23 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Gas 2005-present
GC Numbers 41-415-5841-415-5941-421-4541-421-4641-421-9741-421-9847-349-0847-349-07
Download the Ideal Classic manual
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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. 23 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 |
|---|---|---|
| 41-415-58 | Classic HE 9 | 2005–2011 |
| 41-415-59 | Classic HE 12 | 2005–2011 |
| 41-421-45 | Classic HE 15 | 2005–2011 |
| 41-421-46 | Classic HE 18 | 2005–2011 |
| 41-421-97 | Classic HE 15 P | 2005–present |
| 41-421-98 | Classic HE 18 P | 2005–present |
| 47-349-08 | Classic 30 | 2014–present |
| 47-349-07 | Classic 24 | 2014–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 Classic faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 23 documented codes
Tap any card for details
77
ALTERNATING ‘F’ AND ‘9’ - PCB FAULT
78
ALTERNATING ‘C’ AND ‘0’ - BCC ACTIVATION FAULT
79
ALTERNATING ‘c’ AND ‘2’ - BCC FAULT (BOILER CHIP CARD)
80
ALTERNATING ‘F’ AND ‘7’ - LOW MAINS VOLTAGE
81
NO CH OPERATION BUT HW WORKS OK
82
NO HW BUT CH ON
83
NO DISPLAY
C0
BCC ACTIVATION FAULT
C2
If no BCC fitted on non programmed board “C2” will be displayed
Showing 11–20 of 23
F1
LOW WATER PRESSURE
F2
FLAME LOSS
F3
FAN FAULT
F4
FLOW THERMISTOR FAULT
F5
RETURN THERMISTOR FAULT
F7
LOW MAINS VOLTAGE
F9
PCB FAULT
L and 1
FLOW TEMPERATURE OVERHEAT LOCKOUT
L and 2
IGNITION LOCKOUT
L1
FLOW TEMPERATURE OVERHEAT LOCKOUT
Showing 21–23 of 23
L2
IGNITION LOCKOUT
L5
5 RESETS WITHIN 15 MINS
L6
FALSE FLAME LOCKOUT
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