- Boilers
- Gas boiler
F61
Saunier Duval F.61 on a gas boiler: gas valve control fault
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Saunier Duval F.61 means a gas valve control fault. The causes are in its wiring, the gas valve itself or the electronics. Do not touch anything inside the boiler. Press reset once and wait five seconds; if it stays, call the official service centre.
Safety first
Stop and check this first
- If you smell fumes indoors: Saunier Duval says to open doors and windows fully, switch the appliance off and call a professional. Poor combustion or fumes that do not clear properly can fill the home with carbon monoxide, which has no smell: if you feel headache, dizziness or nausea, ventilate, get out and call for help. A CO alarm helps.
- If you smell gas: Saunier Duval says to keep away from the area, open doors and windows, light no flames and do not smoke, do not touch switches, sockets, doorbells or phones, close the meter and appliance gas valves, warn neighbours without the bell, leave the building and call the gas company from a phone outside.
- Do not touch the gas valve or its screws. Saunier Duval forbids tampering with the Offset adjustment screw, sealed at the factory, and reserves gas adjustments for a qualified installer.
Safe checks you can perform
- Code on the display and other codes
- Recent work on the boiler
- One reset with the fault key
- Harness and gas valve checked by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Insulation of the harness to the gas valve
- Do not attempt this professional task: Gas valve coils
- Do not attempt this professional task: Tightness and combustion after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Insulation of the harness to the gas valve
What they doThe technician disconnects the gas valve and measures whether any harness wire to it shorts to earth.
They must show youthe harness measurement with the gas valve disconnected.
In writingwhether there was a short and what was repaired.
Gas valve coils
What they doMeasures the gas valve coils against earth to see whether the short is in the part itself.
They must show youthe measured value against the manufacturer's specification.
In writingthe value and, if the gas valve is replaced, its reference and why.
Tightness and combustion after the repair
What they doIf the gas valve is replaced, checks the tightness of the gas pipe and measures CO2 with test programme P.01 at 100 once the reading is stable.
They must show youthe tightness test and the measured CO2 against the manufacturer's table.
In writingboth results.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Code on the display and other codes
- Who:
- you.
- How:
- take a photo of the display. If several faults are present, Saunier Duval shows them alternately every two seconds: wait a few seconds and note them all.
- Result that matters:
- whether F.61 appears alone or alternates with other codes.
- If it appears alone:
- the fault is in the gas valve control; go on to the next check.
- If it alternates with others:
- note them all; the technician needs them for the diagnosis.
- Evidence to keep:
- photos of the display with date and time.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Recent work on the boiler
- Who:
- you.
- How:
- think back to whether anyone opened the boiler recently for a service or a repair.
- Result that matters:
- whether F.61 started right after it.
- If it started after some work:
- tell the technician; ask them to check the harness to the gas valve first where the work was done.
- If there was no work:
- the cable, gas valve or electronics may have failed on their own; the technician separates them by measuring.
- Evidence to keep:
- date and report of the last service.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00 · Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
One reset with the fault key
- Who:
- you.
- How:
- press the fault clearing (reset) key and wait five seconds, as Saunier Duval describes. Do it once only.
- Result that matters:
- whether F.61 comes back.
- If it clears and stays away:
- note the date and tell the technician at the next service.
- If it persists or returns:
- do not keep resetting; call the official service centre.
- Evidence to keep:
- a photo of the display with the code and the time.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Harness and gas valve checked by the technician
- Who:
- official service centre technician or qualified installer.
- How:
- with the boiler powered off, disconnects the gas valve, checks whether the harness or the coils short to earth and, if both are fine, checks the electronics.
- Result that matters:
- where the short to earth is.
- If the harness shorts to earth:
- the harness is repaired or replaced, not the gas valve.
- If the coils short to earth:
- the gas valve is replaced and tightness and combustion are checked.
- Evidence to keep:
- a report with what was measured and replaced.
The gas valve, the flame and the flue are gas and combustion parts. Saunier Duval reserves this work for a qualified installer: do not open the casing.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Saunier Duval
- Product type
- Gas boiler
Known code variants
- 61
- code erreur F61 chaudière Vaillant
- codice F61 Vaillant
- código F61 Vaillant
- error F61 caldera Vaillant
- Error F61 Saunier Duval
- errore F61 caldaia Vaillant
- F 61
- Fehlercode F61 Vaillant
- panne F61 Vaillant
- Saunier Duval F.61
- ThemaFast Condens F.61
- Vaillant boiler F61
- Vaillant F.61
- Vaillant F61
- Vaillant Fehler F61
What it means
In the ThemaFast Condens table, F.61 is gas valve control fault. Saunier Duval gives three causes: a short to earth in the wiring harness to the gas valve, a faulty gas valve with its coils shorted to earth and an electronics fault. The gas valve controls gas flow to the burner. Unlike F.26, which flags the valve not working and points to the stepper motor, F.61 points to a short to earth. The code does not separate the cable from the coil.
Warnings and stop conditions
- Higheditorial warning
If you smell fumes indoors: Saunier Duval says to open doors and windows fully, switch the appliance off and call a professional. Poor combustion or fumes that do not clear properly can fill the home with carbon monoxide, which has no smell: if you feel headache, dizziness or nausea, ventilate, get out and call for help. A CO alarm helps.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
- Criticalsource verified
If you smell gas: Saunier Duval says to keep away from the area, open doors and windows, light no flames and do not smoke, do not touch switches, sockets, doorbells or phones, close the meter and appliance gas valves, warn neighbours without the bell, leave the building and call the gas company from a phone outside.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
- Highsource verified
Do not touch the gas valve or its screws. Saunier Duval forbids tampering with the Offset adjustment screw, sealed at the factory, and reserves gas adjustments for a qualified installer.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00 · Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Symptoms and causes
Probable causes · in order
- Harness to the gas valve shorted to earthPossible
A cable shorting to earth on the run to the gas valve gives F.61. The technician separates it by measuring the harness with the gas valve disconnected.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
- Gas valve coils shorted to earthPossible
If the cable is fine, the short may be in the gas valve coils. Then the faulty part is the gas valve, which only a qualified technician handles.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
- Electronics faultLess common
If harness and coils are fine, the circuit board remains. It is the last cause Saunier Duval lists for F.61.
Evidence: Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
Virtual technician
Does F61 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Saunier Duval ThemaFast Condens, instrucciones de instalación y mantenimiento 0020238203_00
Saunier Duval · 2016 · manual
- 2
Saunier Duval ThemaFast Condens, instrucciones de funcionamiento 0020238204_00
Saunier Duval · 2016 · manual
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