Viessmann Vitodens 100-W F.357 — Burner in a Fault State
F.357
Burner in a fault state. The gas supply is insufficient; check that the gas shut-off valve is open and the solenoid valve input-side screen is clean, test the static and flow gas pressures and confirm the on-site gas line is correctly sized, check the fuel valve coil resistance and the ignition electrode, then reset the boiler.
If you smell gas
- Stop what you are doing. Do not use phones, switches, matches or anything that can spark inside.
- Go outside and leave the door open behind you.
- Call the FortisBC 24-hour emergency line at 1-800-663-9911 or dial 911.
Only after that, call ROMA about the boiler. Official guidance: FortisBC gas leaks and odour.
Applies to
This ignition fault code is displayed by the HMU-BCU control (3.5" display) on Vitodens 100-W B1HE heating-only and B1KE combi models (B1HE-85, B1HE-120, B1HE-150, B1HE-199, B1KE-120, B1KE-199), as documented in Installation and Service Instructions — Vitodens 100-W B1HE/B1KE, doc 6167 818 - 22, troubleshooting fault messages (6167 818 - 22). Codes can differ between controller generations, so always check the manual that matches your unit.
- Viessmann Vitodens 100-W (B1HE / B1KE)
- Viessmann Vitodens 100-W B1HE-85
- Viessmann Vitodens 100-W B1HE-120
- Viessmann Vitodens 100-W B1HE-150
- Viessmann Vitodens 100-W B1HE-199
- Viessmann Vitodens 100-W B1KE-120
- Viessmann Vitodens 100-W B1KE-199
Controller: HMU-BCU control (3.5" display). Source manual: 6167 818 - 22 (2026-02).
Why a code is not a diagnosis
An ignition code says the burner did not prove a flame when it should have; it does not say why. Gas supply, ignition components, grounding, venting and the control module each need testing on site.
Safe things to observe
- If you smell gas, stop, go outside and call your gas utility's emergency line or 911 before anything else.
- Note the exact code and what the appliance was doing when it appeared.
- Check whether other gas appliances in the building are working.
Do not
- Do not keep resetting to force more ignition attempts.
- Do not open the gas valve, touch ignition components or bypass any safety device.
How professional service helps
- A licensed gas technician tests gas supply pressure and the shut-off state.
- The ignition probe, lead, gap and grounding are inspected against the manufacturer's specification.
- Combustion and safety devices are verified with an analyser and the manufacturer's procedure after any repair.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Parts and service
Parts commonly involved
These parts appear in the documented text for this alert. A code reports a condition, not a failed part — a technician confirms the cause by testing before anything is replaced.
Ignition electrode
The ignition electrode creates the spark that lights the burner in a gas boiler, and on many models it also senses the flame once it is burning.
What a technician checks →Burner assembly
The burner assembly is where gas and air meet and burn inside a boiler, and its condition decides whether combustion is clean or makes carbon…
What a technician checks →
Service for this alert
- Gas Boiler Repair
Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…
- Emergency Boiler Repair
Priority gas boiler repair for homes and buildings in Greater Vancouver with no heat, no hot water, a locked-out boiler or a leak.
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for Viessmann Vitodens 100-W (B1HE / B1KE).
Frequently asked questions
Does this code mean I have a gas leak?
Not by itself. If you smell gas, stop, leave the building and call your gas utility's emergency line or 911 from outside before anything else. Otherwise the code points to a fault a technician confirms on site.
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- Installation and Service Instructions — Vitodens 100-W B1HE/B1KE, doc 6167 818 - 22, troubleshooting fault messages · 6167 818 - 22 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.