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

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

The codes below apply across common Vaillant models (ecoTEC plus, ecoTEC pro, ecoFIT). Meanings follow Vaillant’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 Vaillant boiler error codes

Vaillant uses an 'F.' prefix with a number (e.g. F.22, F.28); most also display a leading zero. A 'con' message indicates a lost connection between the PCB and display rather than a numbered fault.

Vaillant boiler error codes & what they mean

These are the Vaillant 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
F.0	Flow temperature sensor (flow NTC) interrupted / open circuit pro repair	faulty flow NTC sensor; loose or corroded sensor wiring/plug; wiring harness break to PCB	press the reset button once; if it recurs immediately, stop and call a licensed technician
F.1	Return temperature sensor (return NTC) interrupted / open circuit pro repair	faulty return NTC sensor; loose or corroded sensor connection; wiring break to PCB	press the reset button once
F.10	Flow temperature sensor (flow NTC) short circuit pro repair	shorted flow NTC sensor; pinched/damaged sensor wiring; moisture in the connector	press the reset button once
F.11	Return temperature sensor (return NTC) short circuit pro repair	shorted return NTC sensor; damaged sensor wiring; moisture in connector	press the reset button once
F.13	Cylinder / hot water tank temperature sensor (NTC) short circuit pro repair	shorted cylinder NTC sensor; damaged cylinder sensor wiring; connector fault	press the reset button once
F.20	Safety shutdown: safety temperature limiter (overheat cut-out) has operated pro repair	overheating due to poor circulation; faulty flow/return NTC sensor giving wrong reading; loose sensor/earth connection	check that radiators/system valves are open so the pump can circulate; check system pressure is in the normal range; press the reset button once
F.22	Low water pressure / dry-fire protection (insufficient water in the boiler) pro repair	low system pressure / water loss from a leak; faulty water pressure sensor; pump not running or air-locked	read the pressure gauge; if low, top up via the filling loop per the user manual; look for visible leaks around the boiler and radiators; press the reset button once after re-pressurising
F.23	Temperature spread between flow and return sensors too large (possible low water / circulation fault) pro repair	poor circulation / low flow; pump fault or air in the system; flow and return sensors transposed	check system pressure is in the normal range; confirm radiator/isolation valves are open; press the reset button once
F.24	Temperature rising too quickly (possible water shortage / circulation fault) pro repair	low water flow / poor circulation; pump not running or seized; air in the system	check system pressure is normal; ensure system valves are open; press the reset button once
F.27	Safety shutdown: flame signal detected while the burner should be off pro repair	faulty gas valve (leaking through); moisture on the electronics; faulty flame-sensing electrode/PCB	press the reset button once; do not attempt gas-side checks; if it recurs call a licensed technician
F.28	Ignition failure during start-up (no flame established on start) pro repair	no gas supply / gas tap closed or low pressure; faulty gas valve; ignition electrode/lead or PCB fault	confirm the gas supply is on and other gas appliances work; check the condensate drain is not blocked or frozen; press the reset button once (no more than 2-3 times)
F.29	Flame lost during operation and re-ignition unsuccessful pro repair	interrupted or fluctuating gas supply; faulty gas valve; ignition/flame-sensing electrode or PCB fault	confirm the gas supply is on and other gas appliances work; press the reset button once
F.32	Fan fault (fan speed out of range) pro repair	faulty or seized fan; fan wiring/connector fault; blocked flue affecting fan	press the reset button once
F.49	eBUS fault / under-voltage pro repair	eBUS wiring short circuit or fault; faulty connected control/accessory; polarity or wiring error on eBUS	press the reset button once
F.54	Gas supply fault (recorded with F.28/F.29) pro repair	no or low gas supply pressure; gas tap partially closed; gas valve fault	confirm the gas supply is on and other gas appliances work; do not attempt gas-side checks; call a licensed technician
F.61	Gas valve control fault (electronics) pro repair	faulty gas valve; short circuit in gas valve wiring; PCB / gas valve control fault	press the reset button once
F.62	Gas valve shut-off delay fault pro repair	faulty gas valve (delayed closing); flame sensing electrode fault; PCB fault	press the reset button once
F.63	EEPROM error (electronics memory fault) pro repair	faulty PCB / corrupted memory; electronics fault	press the reset button once
F.64	Electronics / NTC fault pro repair	flow or return NTC short circuit; faulty PCB	press the reset button once
F.65	Electronics temperature too high pro repair	PCB overheating; faulty electronics/PCB; external heat source on the boiler	press the reset button once
F.67	Flame detector input signal out of range (implausible flame signal) pro repair	faulty PCB; flame-sensing electrode fault	press the reset button once
F.70	Invalid Device Specific Number (DSN) – display/PCB coding mismatch pro repair	spare-part display or PCB replaced without setting correct DSN; mismatched or missing coding resistor	no safe homeowner action; call a licensed technician (occurs after a part replacement)
F.72	Flow and/or return temperature sensor fault (implausible temperature spread) pro repair	faulty flow or return NTC sensor; sensor wiring fault; sensors transposed	press the reset button once
F.73	Water pressure sensor signal out of range / too low pro repair	faulty water pressure sensor; pressure sensor wiring/connector fault; disconnected sensor	check the pressure gauge reading; press the reset button once
F.75	No pressure rise detected when the pump starts (pump / water pressure sensor fault) pro repair	faulty water pressure sensor; faulty or air-locked pump; sludge/blockage in the system	check system pressure and top up if low per the user manual; press the reset button once
F.77	Condensate pump / flue accessory feedback fault (heating blocked) pro repair	faulty or blocked condensate pump; flue damper/accessory feedback fault; wiring fault	check the condensate drain/pump area for an obvious blockage or freeze; press the reset button once
F.83	Little or no temperature change at the flow/return sensor when the burner starts pro repair	low water content / low pressure; air in the boiler; sensor not making good thermal contact	check system pressure and top up if low; press the reset button once
F.84	Implausible difference between flow and return temperature sensors pro repair	flow and return sensors transposed; faulty NTC sensor; sensor wiring fault	press the reset button once
con	No communication / connection lost between the PCB and the display or control unit pro repair	eBUS / interface wiring fault; faulty display or control; loose connector	check the room thermostat/control batteries if applicable; restore power at the isolator and wait for it to re-establish

Vaillant boiler codes we get called for most

F.28 — Ignition failure during start-up (no flame established on start)

Typical causes include no gas supply / gas tap closed or low pressure; faulty gas valve; ignition electrode/lead or pcb fault. A few things are safe to check yourself (confirm the gas supply is on and other gas appliances work; check the condensate drain is not blocked or frozen), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes F.28 on Vaillant boilers throughout Greater Vancouver.

F.29 — Flame lost during operation and re-ignition unsuccessful

Typical causes include interrupted or fluctuating gas supply; faulty gas valve; ignition/flame-sensing electrode or pcb fault. A few things are safe to check yourself (confirm the gas supply is on and other gas appliances work; press the reset button once), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes F.29 on Vaillant boilers throughout Greater Vancouver.

F.22 — Low water pressure / dry-fire protection (insufficient water in the boiler)

Typical causes include low system pressure / water loss from a leak; faulty water pressure sensor; pump not running or air-locked. A few things are safe to check yourself (read the pressure gauge; if low, top up via the filling loop per the user manual; look for visible leaks around the boiler and radiators), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes F.22 on Vaillant boilers throughout Greater Vancouver.

F.20 — Safety shutdown: safety temperature limiter (overheat cut-out) has operated

Typical causes include overheating due to poor circulation; faulty flow/return ntc sensor giving wrong reading; loose sensor/earth connection. A few things are safe to check yourself (check that radiators/system valves are open so the pump can circulate; check system pressure is in the normal range), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes F.20 on Vaillant boilers throughout Greater Vancouver.

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

Most Vaillant 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.

Vaillant boiler repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Vaillant 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.

Vaillant boiler service areas

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

Vaillant boiler error code FAQs

Can I reset my Vaillant 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 Vaillant F.0 code mean?

On Vaillant boilers, F.0 commonly indicates flow temperature sensor (flow ntc) interrupted / open circuit. 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 Vaillant boilers you didn’t install?

Yes. HeatLand is brand-agnostic and services Vaillant 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 Vaillant 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 Vaillant boiler repair cost in Vancouver?

It depends on the fault. Many Vaillant 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

HeatLand repairs every major boiler brand across Greater Vancouver. More brand guides: