Viessmann Boiler Error Codes — Meanings, Causes & Repair in Greater Vancouver

Seeing a fault code on your Viessmann boiler? This guide explains what the most common Viessmann boiler error codes mean, what’s safe to check yourself, and when to call HeatLand’s licensed, TSBC-certified gas technicians for Viessmann boiler repair across Metro Vancouver and the Fraser Valley.

The codes below apply across common Viessmann models (Vitodens 100-W (B1HA/B1KA), Vitodens 200-W (B2HA/B2HB/B2HE), Vitodens 222-F). Meanings follow Viessmann’s documented fault codes — always confirm against your unit’s own manual, because exact wording can vary by model, control board and firmware.

How to read Viessmann boiler error codes

On the digital display the boiler shows a wrench/spanner fault symbol plus a two-character fault code (e.g. 'F4', 'F2', 'EE', '0A'). When the symbol flashes with 'R' shown, the burner is locked out and a manual reset (press and hold the reset button 'R') is required. On Vitodens 200-W the control may also log a numeric 'Detailed Code' alongside the displayed fault code. Note: Canadian/North-American Vitodens manuals print codes as 'F4', 'F2', etc. (no dot); UK literature often writes the same codes as 'F.4', 'F.2'.

Viessmann boiler error codes & what they mean

These are the Viessmann boiler codes our Greater Vancouver technicians see most. Anything marked pro repair involves gas, electrical, sealed-combustion or control-board work that must be done by a licensed gas technician (TSBC-certified in BC) — never open gas or electrical components yourself.

Code	What it usually means	Common causes	Safe to check yourself
0A	Burner blocked: CO limiter (if installed) has responded because CO concentration is too high, OR the gas pressure switch (if installed) has responded because gas supply pressure is too low pro repair	Combustion problem causing elevated CO; Low or interrupted gas supply pressure; Blocked or restricted flue/air intake	Confirm the gas supply is turned on at the meter/shut-off valve; Confirm nothing is blocking the outdoor flue terminal (snow, leaves, debris); Do NOT investigate combustion or CO yourself — this is a safety lockout; book a licensed gas technician
0b	Burner blocked: low water, or the pump or flow switch is defective pro repair	Low system water pressure; Circulation pump fault; Faulty flow switch	Read the system pressure gauge — if it is below the normal band (typically ~12-22 psi / ~1.0-1.5 bar cold), pressure is low; Try one reset after noting the pressure; If pressure is low or the fault returns, call a licensed technician
0C	Burner blocked: mains (electrical supply) voltage too low pro repair	Low or unstable household electrical supply; Power dip/brownout; Loose or shared circuit	Confirm the boiler's power switch and the wall outlet/breaker are on; Check whether other appliances on the same circuit are affecting power; Reset once; if it recurs, call a licensed technician (do not open electrical covers)
10	Outdoor temperature sensor short-circuited; boiler reverts to constant (fixed) operating mode pro repair	Faulty outdoor temperature sensor; Damaged sensor wiring; Moisture in the sensor	No safe homeowner action — heating still runs in constant mode; Report the code to a licensed technician for sensor diagnosis
18	Outdoor temperature sensor wire broken (open circuit); boiler reverts to constant (fixed) operating mode pro repair	Broken or disconnected outdoor sensor wiring; Failed outdoor temperature sensor	No safe homeowner action — heating still runs in constant mode; Report to a licensed technician for sensor/wiring check
30	Burner blocked: boiler water temperature sensor short-circuited pro repair	Faulty boiler water temperature sensor; Damaged sensor wiring/connector	No safe homeowner action — internal sensor; Call a licensed technician
38	Burner blocked: boiler water temperature sensor wire broken (open circuit) pro repair	Broken sensor wire or loose connector; Failed boiler water temperature sensor	No safe homeowner action — internal sensor; Call a licensed technician
50	No DHW (hot water) heating: DHW tank temperature sensor short-circuited pro repair	Faulty tank temperature sensor; Damaged sensor wiring	No safe homeowner action — internal sensor; Heating may still work; call a licensed technician for hot water issue
51	No DHW (hot water) heating: DHW outlet temperature sensor short-circuited pro repair	Faulty DHW outlet sensor; Damaged sensor wiring	No safe homeowner action — internal sensor; Call a licensed technician
52	Burner blocked: flow sensor short-circuited pro repair	Faulty flow sensor; Damaged connector or wiring	No safe homeowner action — internal component; Call a licensed technician
58	No DHW (hot water) heating: DHW tank temperature sensor wire broken (open circuit) pro repair	Broken/disconnected tank sensor wire; Failed tank temperature sensor	No safe homeowner action — internal sensor; Call a licensed technician
59	No DHW (hot water) heating: DHW outlet temperature sensor wire broken (open circuit) pro repair	Broken/disconnected outlet sensor wire; Failed DHW outlet sensor	No safe homeowner action — internal sensor; Call a licensed technician
5A	Burner blocked: flow sensor wire broken (open circuit) pro repair	Broken/disconnected flow sensor wire; Failed flow sensor	No safe homeowner action — internal component; Call a licensed technician
A3	Burner blocked: flue gas temperature sensor incorrectly positioned (no flame formation during the sensor test) pro repair	Flue gas temperature sensor not seated correctly; Sensor displaced during service	No safe homeowner action — internal flue sensor; Call a licensed technician to reposition/test
b0	Burner blocked: flue gas temperature sensor short-circuited pro repair	Faulty flue gas temperature sensor; Damaged sensor wiring	No safe homeowner action — internal flue sensor; Call a licensed technician
b7	Emergency mode: burner control unit fault (on Vitodens 200-W, B7 also appears together with FD when the boiler coding card is missing) pro repair	Control unit fault; Missing/loose boiler coding card (200-W)	Reset once; If it recurs, call a licensed technician — this is a control-board level fault
b8	Burner blocked: flue gas temperature sensor wire broken (open circuit) pro repair	Broken/disconnected flue gas sensor wire; Failed flue gas temperature sensor	No safe homeowner action — internal flue sensor; Call a licensed technician
E3	Burner in fault mode: fault in the safety chain (e.g. fixed high-limit circuit) pro repair	Fixed high-limit thermostat tripped/faulty; Wiring fault in the safety chain; Control unit fault	Reset once; If it recurs, stop and call a licensed technician — this is a safety device
E5	On Vitodens 100-W: burner blocked due to internal fault (flame amplifier / ionization). On Vitodens 200-W: burner blocked, flame amplifier fault — replace control unit pro repair	Ionization electrode or its lead faulty; Flame amplifier / control board fault	Reset once; If it recurs, call a licensed technician (do not open the burner)
EE	Burner in fault mode: at burner start the flame signal is missing or too weak (boiler tried to light but did not detect a flame) pro repair	Gas supply/pressure problem or gas off; Ignition or ionization electrode fault; Blocked or frozen condensate drain	Confirm the gas supply is on at the shut-off valve; Confirm other gas appliances work (rules out a wider gas outage); Check the condensate drain hose/pipe is not frozen or blocked (common in Vancouver cold snaps)
EF	Burner in fault mode: flame is lost immediately after it is established (during the safety time) pro repair	Gas pressure/regulator issue; Flue gas recirculation; Ionization electrode fault or contamination	Confirm gas supply is on; Reset once; If it recurs, call a licensed technician
F0	Burner blocked: internal control fault — control unit must be replaced pro repair	Internal control unit (PCB) fault	Reset once; If it recurs, call a licensed technician — this requires a control board replacement
F1	Burner in fault mode: maximum flue gas temperature exceeded (200-W documents the limit as ~230°F / 110°C) pro repair	Low system water level / trapped air; Circulation pump not running properly; Scaling restricting flow	Read the system pressure gauge and note if it is low; Allow the boiler to cool, then reset once (200-W: reset only after the flue system has cooled); If it recurs, call a licensed technician
F2	Burner in fault mode: fixed high-limit has tripped (overheat / high-limit safety cut-out) pro repair	Low system water level / low pressure; Trapped air in the system; Circulation pump fault restricting flow	Read the system pressure gauge — top up only if you have been shown how and it is documented for your boiler; otherwise leave it; Allow the boiler to cool fully; Reset once; if it recurs, call a licensed technician
F3	Burner in fault mode: flame signal is already present at burner start (a flame is detected before ignition is commanded) pro repair	Faulty ionization electrode or its connecting cable; Gas valve not closing fully	Reset once; If it recurs, call a licensed technician (gas-safety related)
F4	Burner in fault mode: no flame signal is present (the boiler attempted to ignite but no flame was detected / established) pro repair	Gas off or low gas pressure; Ignition or ionization electrode fault; Faulty gas valve or ignition module	Confirm the gas supply is on at the shut-off valve; Confirm other gas appliances work (rules out a wider outage); Check the condensate drain is not frozen or blocked (common in Vancouver winters)
F8	Burner in fault mode: the combination gas valve closes too late pro repair	Faulty gas valve; Gas-valve control wiring/connection fault	Reset once; If it recurs, call a licensed technician — do not work on the gas valve
F9	Burner in fault mode: blower (fan) speed too low at burner start pro repair	Faulty fan/blower; Fan wiring or power supply fault; Fan control fault	Reset once; If it recurs, call a licensed technician
FA	Burner in fault mode: blower (fan) not at standstill (fan failed to stop when expected) pro repair	Fan/blower fault; Fan connecting cable fault; Fan control fault	Reset once; If it recurs, call a licensed technician
FC	On Vitodens 100-W: burner blocked, electrical fan control (control unit) faulty. On Vitodens 200-W: gas valve faulty / faulty modulation valve control, or the vent system is blocked pro repair	Fan control / control unit fault (100-W); Faulty gas/modulation valve or blocked vent system (200-W)	On 200-W, confirm the outdoor flue terminal is not blocked (snow, debris); Reset once; If it recurs, call a licensed technician
FD	Burner in a fault state (additional fault B7 also shown): boiler coding card is missing pro repair	Boiler coding card missing or not seated; Control unit fault if card is present	No safe homeowner action — internal coding card; Call a licensed technician
FE	Burner in fault mode: damaged or incorrect boiler coding card or main PCB pro repair	Damaged/incorrect coding card; Main control board (PCB) fault; Strong electromagnetic interference	Reset once; If it recurs, call a licensed technician
FF	Burner in fault mode: internal fault, or the reset button 'R' is blocked/stuck pro repair	Stuck reset button; Internal control fault	Restart the equipment (power cycle) once; If it will not restart, call a licensed technician

Viessmann boiler codes we get called for most

A3 — Burner blocked: flue gas temperature sensor incorrectly positioned (no flame formation during the sensor test)

Typical causes include flue gas temperature sensor not seated correctly; sensor displaced during service. A few things are safe to check yourself (No safe homeowner action — internal flue sensor; Call a licensed technician to reposition/test), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes A3 on Viessmann boilers throughout Greater Vancouver.

0A — Burner blocked: CO limiter (if installed) has responded because CO concentration is too high, OR the gas pressure switch (if installed) has responded because gas supply pressure is too low

Typical causes include combustion problem causing elevated co; low or interrupted gas supply pressure; blocked or restricted flue/air intake. A few things are safe to check yourself (Confirm the gas supply is turned on at the meter/shut-off valve; Confirm nothing is blocking the outdoor flue terminal (snow, leaves, debris)), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 0A on Viessmann boilers throughout Greater Vancouver.

F9 — Burner in fault mode: blower (fan) speed too low at burner start

Typical causes include faulty fan/blower; fan wiring or power supply fault; fan control fault. A few things are safe to check yourself (Reset once; If it recurs, call a licensed technician), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes F9 on Viessmann boilers throughout Greater Vancouver.

Is it safe to keep running a Viessmann boiler with a fault code?

Most Viessmann fault codes put the boiler into a safe lockout for a reason. You can safely check the basics — gas supply on, power on, the thermostat calling for heat, system pressure in the normal range, and the condensate drain not frozen or blocked (a common cause in Vancouver cold snaps) — and restart it once. If the code returns, stop and book a technician. If you ever smell gas, leave the building and call your gas utility’s emergency line or 911 first. If a carbon-monoxide alarm sounds, get everyone out and call 911.

Viessmann boiler repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Viessmann boilers — ignition faults, flame and sensor errors, low-pressure and pump problems, fan and flue faults, and control-board issues — including units we didn’t install. We’re brand-agnostic, carry common parts, and give you an honest repair-or-replace assessment with upfront pricing and a free estimate. If your boiler is beyond economical repair, we’ll show you right-sized, high-efficiency replacement options and the rebates available.

Need it sorted fast? We offer priority emergency boiler repair. Explore Boiler services, browse all boiler error codes by brand, or request a free estimate.

Viessmann boiler service areas

We repair Viessmann boilers across Greater Vancouver and the Fraser Valley, including:

Viessmann boiler error code FAQs

Can I reset my Viessmann boiler myself?

Yes — power-cycling the reset button once is generally safe after you’ve checked the basics (gas supply on, power on, the thermostat calling for heat, system pressure in the normal range, and the condensate drain not frozen or blocked (a common cause in Vancouver cold snaps)). If the boiler faults again right away, stop and note the code — repeatedly resetting a boiler that keeps locking out can mask a real problem. Call a licensed, TSBC-certified gas technician to diagnose it.

What does the Viessmann 10 code mean?

On Viessmann boilers, 10 commonly indicates outdoor temperature sensor short-circuited; boiler reverts to constant (fixed) operating mode. Confirm the exact meaning against your unit’s manual — codes can vary by model and series — and have the repair done by a licensed, TSBC-certified gas technician. HeatLand fixes this across Greater Vancouver.

Do you repair Viessmann boilers you didn’t install?

Yes. HeatLand is brand-agnostic and services Viessmann boilers throughout Metro Vancouver and the Fraser Valley, whether or not we installed the unit. We carry common parts and give you an honest repair-or-replace assessment.

Is a Viessmann boiler fault code an emergency?

No heat in cold weather is worth treating urgently. If you ever smell gas, leave the building and call your gas utility’s emergency line or 911 first. If a carbon-monoxide alarm sounds, get everyone out and call 911. For priority boiler repair across Greater Vancouver, call (604) 330-3812.

How much does Viessmann boiler repair cost in Vancouver?

It depends on the fault. Many Viessmann codes point to sensors, ignition or pump parts — usually far cheaper than replacement. We give upfront pricing and a free estimate before any work.

More Boiler error-code guides

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