BoilerFaultCodes F2
Flame Loss
Ideal LOGIC HEAT Fault codes & diagnostics
24 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Gas 2016-present
GC Numbers 41-750-7741-750-7841-750-7941-750-8041-750-81
Download the Ideal LOGIC HEAT 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. 24 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 |
|---|---|---|
| 41-750-77 | LOGIC HEAT H12 | 2016–present |
| 41-750-78 | LOGIC HEAT H15 | 2016–present |
| 41-750-79 | LOGIC HEAT H18 | 2016–present |
| 41-750-80 | LOGIC HEAT H24 | 2016–present |
| 41-750-81 | LOGIC HEAT H30 | 2016–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 LOGIC HEAT faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 24 documented codes
Tap any card for details
F3
Fan Fault
F4
Control / No Flow Thermistor Fault
F5
Return Thermistor Fault
F6
Outside Sensor Fault
F7
LOW MAINS VOLTAGE - CONTACT ELECTRICITY PROVIDER
F8
PCB UNCONFIGURED/FAULTY OR GAS VALVE SHORT CIRCUIT
F9
PCB programming mode
FA
Flow / Return Reversed
Fd
No Water Flow
Showing 11–20 of 24
Fn
Flame Loss
FU
DIFF GREATER THAN 50ºC. CHECK ISOLATION VALVES ARE OPEN, CHECK PUMP, CHECK RAD VALVES OPEN, CHECK SYSTEM BLOCKAGES
L1
Flow Temp O’heat or No Water Flow Lockout
L2
Ignition Lockout
L4
Control / No Flow Thermistor Fault
L5
Return Thermistor Fault
L6
False Flame Lockout
L7
<5ºC RISE ON 3 SUCCESSIVE OCCASIONS. CHECK THERMISTORS ARE CLIPPED ONTO PIPES
L8
PCB UNCONFIGURED/FAULTY OR GAS VALVE SHORT CIRCUIT
L9
PCB UNCONFIGURED/FAULTY OR GAS VALVE SHORT CIRCUIT
Showing 21–24 of 24
LC
Boiler lockout after 5 restart attempts within 15 minutes
Ln
Flame Loss
oF
PCB programming mode
uP
PCB programming mode
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