No gas,Insufficient gas, Incorrect gas valve adjustment, Electrode ignition lead defect, Electronic igniter defective, Check air inlet duct, Check connections to igniter unit
The F1 error code on Saunier-Duval boilers indicates no gas,insufficient gas, incorrect gas valve adjustment, electrode ignition lead defect, electronic igniter defective, check air inlet duct, check connections to igniter unit. Symptoms include fault displayed.
Saunier-Duval F1 means: no gas,insufficient gas, incorrect gas valve adjustment, electrode ignition lead defect, electronic igniter defective, check air inlet duct, check connections to igniter unit. The usual causes are faulty or worn ignition electrode, cracked or dirty ignition lead or gas supply interruption or low gas pressure. A Gas Safe registered engineer should diagnose the root cause.
What Does F1 Mean
The F1 code is shown by the boiler’s control board when it detects no gas,insufficient gas, incorrect gas valve adjustment, electrode ignition lead defect, electronic igniter defective, check air inlet duct, check connections to igniter unit. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| FAULT DISPLAYED |
Common Causes
Causes documented in 2 technical sources.
| Cause |
|---|
| Faulty or worn ignition electrode |
| cracked or dirty ignition lead |
| gas supply interruption or low gas pressure |
| blocked condensate drain preventing ignition |
| defective gas valve not opening |
| faulty PCB (printed circuit board) not sending ignition signal |
Safety Warning
F1 is a gas-related fault. Never attempt to repair or adjust the gas valve, burner assembly, or flue system yourself. All gas work must be carried out by a Gas Safe registered engineer (UK) or licensed HVAC technician (US). Repeated resets after ignition failure can cause unburnt gas to accumulate inside the combustion chamber — this is a serious safety hazard. If you smell gas at any point, turn off the gas supply at the meter, open windows, leave the property, and call your gas emergency service immediately. Code défaut lié au gaz. N'ouvrez pas le coffret de la chaudière et ne tentez pas de réparer vous-même le robinet de gaz, le brûleur, l'allumage ou les conduits de fumée. Les réinitialisations répétées sont dangereuses. Faire intervenir un professionnel certifié.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
How to Fix It
Clean or replace the ignition electrode and lead
clear any condensate blockage (pour warm water over frozen external pipe in winter)
reset the boiler after checking all components
if the gas valve is not opening, replace the gas valve (Gas Safe registered engineer required)
if the PCB is not sending ignition signal, replace the PCB. Important: all gas work must be carried out by a Gas Safe registered engineer
Refer to the Saunier-Duval service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Saunier-Duval models that can display fault code F1:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Saunier-Duval models | — | Possible |
Frequently Asked Questions
Clean or replace the ignition electrode and lead. According to the technical documentation, this is the first check on the list for F1.
F1 is classified as a high-severity fault: it involves gas, combustion or flue components. Do not keep resetting the boiler and do not attempt the repair yourself — call a Gas Safe registered engineer.