Main board fault
The F13 error code on Saunier-Duval boilers indicates main board fault.
Saunier-Duval F13 means: main board fault. On this component the documented failure modes are wiring, connector or harness of the control board damaged or loose or control board (pcb) faulty. A Gas Safe registered engineer should diagnose the root cause.
What Does F13 Mean
The F13 code is shown by the boiler’s control board when it detects main board fault. 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 |
|---|
| The display shows F13 and the boiler stops until the fault is cleared |
Common Causes
The manufacturer does not publish a cause list for this specific code. The causes below are the failure modes documented for the same component on other boilers, confirmed by the service literature of 5 different manufacturers.
| Cause |
|---|
| Wiring, connector or harness of the control board damaged or loose |
| Control board (PCB) faulty |
Safety Warning
F13 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. Warning: this fault code may relate to gas supply, flue or combustion issues. Do not attempt repair — contact a Gas Safe registered engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
F13 Main board connection fault Check connection and wires F14 Central heating flow T° > 95°C (203 °F) System fault / Possible pump failure Check thermistor on flow F16 Flame detection fault (flame presence for more than 5 seco
How to Fix It
Reset the boiler after investigation
repair any loose connections or damaged wiring
replace the faulty component identified during diagnosis
if the fault persists after basic checks, contact a qualified heating engineer with the exact error code
Unplug and re-seat the connector of the control board, then check the harness for chafing, corroded pins and breaks in continuity.
Only after every other check: verify the board’s supply and connections, and replace the board — fitting the correct boiler chip card or coding key where the model requires one.
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 F13:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Saunier-Duval models | — | Possible |
Frequently Asked Questions
Reset the boiler after investigation. According to the technical documentation, this is the first check on the list for F13.
F13 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.