Slant/Fin Boiler Error Codes — Meanings, Causes & Repair in Greater Vancouver

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

The codes below apply across common Slant/Fin models (CHS, VSL, Sentry). Meanings follow Slant/Fin’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 Slant/Fin boiler error codes

CHS uses the SOLA control which displays Hold (temporary), Lockout (requires manual reset) and Alert (informational) codes as a word + number, e.g. "Lockout 67 ILK OFF" or "Hold 110 Ignition failure". VSL / VSL II uses a different control that displays lockout codes as "Loc" + number (Loc 01-37, resettable with RESET key) and permanent blocking errors as "Err" + number (Err 45-116, cannot be reset until the cause is corrected). The conventional cast-iron Sentry boiler uses a Fuel Smart HydroStat control with indicator LEDs and short text abbreviations (e.g. LCO/LWCO low-water blink) rather than numbered fault codes.

Slant/Fin boiler error codes & what they mean

These are the Slant/Fin 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
Lockout 2	Waiting for safety data verification (CHS / SOLA control internal startup fault) pro repair	Faulty SOLA controller	Confirm the boiler has power; Try one single reset using the controller reset button
Hold 27	Flame sensor shorted to ground detected (a flame circuit short can show up as a flame circuit timeout) pro repair	Condensate drain blocked; External voltage applied to R & CH terminals; 4-20mA input current too high (over 21mA)	Check that the condensate drain line and trap are not blocked or frozen and that condensate is flowing out; Try one single reset
Hold 61	Anti short-cycle delay active (normal operation; burner is waiting out a timer) DIY-checkable	Normal operation – the control is enforcing a minimum off-time between burner cycles	No action usually needed – allow the timer to expire and the burner will resume
Hold 62	Fan (blower) speed not proved pro repair	Normal momentarily before ignition (Drive to Lightoff); Blown fuse A preventing blower operation; Blower wiring/connector defect	Confirm the boiler has power; Try one single reset
Hold 67	ILK OFF – interlock open (commonly a low-water condition or an open external limit wired to LIM) pro repair	Low water condition in the boiler; Internal low-water cut-off (LWCO) tripped; External limit device (wired to LIM) is open	Check the boiler system pressure gauge – low pressure can indicate low water; Try one single reset; if it returns, call a technician
Lockout or Hold 79	Outlet high limit – boiler outlet water temperature exceeded the high-limit setpoint (factory 200F / 93C) pro repair	CH or DHW setpoint plus hysteresis exceeds the high-limit setpoint; CH or DHW pump problem / insufficient flow; Incorrect outlet high limit or high-limit response setting	Check that the heating system has adequate water pressure on the gauge; Confirm the thermostat is not calling for an unreasonably high temperature; Try one single reset
Lockout or Hold 81	Delta-T limit – temperature rise across the boiler too high (often accompanied by banging or hissing), indicating insufficient water flow pro repair	Insufficient water flow; Blown fuse B; Appliance (boiler) pump problem	Check that water pressure on the gauge is at least 15 PSI; Try one single reset
Lockout 82	Stack limit – flue/stack exhaust gas temperature exceeded the stack high-limit setpoint pro repair	Dirty heat exchanger / combustion chamber; Incorrect stack limit setpoint	Try one single reset; if it returns, the boiler needs cleaning/service
Lockout 85	Inlet/Outlet inversion limit – inlet and outlet temperatures are inverted (pump flowing in the wrong direction) pro repair	Pump installed/flowing in the wrong direction	No safe homeowner action – this is an installation/flow-direction issue for a technician
Lockout or Hold 88	Outlet T-Rise limit – rate of outlet temperature rise too fast, indicating insufficient water flow pro repair	Insufficient water flow (same causes as Delta-T limit / Lockout 81)	Check that water pressure on the gauge is at least 15 PSI; Try one single reset
Hold 91	Inlet sensor fault – boiler inlet (return) temperature sensor reading invalid pro repair	Sensor disconnected; Faulty sensor	No safe homeowner action – sensor diagnosis requires opening the unit; call a technician
Hold 92	Outlet sensor fault – boiler outlet (supply) temperature sensor reading invalid pro repair	Sensor disconnected; Faulty sensor	No safe homeowner action – sensor diagnosis requires opening the unit; call a technician
Hold 95	Stack sensor fault – flue/stack temperature sensor reading invalid pro repair	Sensor disconnected; Faulty sensor	No safe homeowner action – sensor diagnosis requires opening the unit; call a technician
Lockout 109 or Hold 110	Ignition failure – failure to prove flame after 3 (CHS) ignition attempts pro repair	Manual gas shutoff valve closed / insufficient gas pressure; Spark cable or flame rod disconnected; Blocked venting / air-inlet	Confirm the gas supply is turned on and other gas appliances work; Confirm the boiler has power; Try one single reset; if it fails again, call a technician
Lockout 113	Flame circuit timeout (a flame circuit shorted to ground can show up as Lockout 113) pro repair	Condensate drain blocked; Voltage applied to R & CH terminals; 4-20mA input current too high (over 21mA)	Check that the condensate drain line and trap are not blocked or frozen; Try one single reset
Lockout 122	Light-off rate proving failed – blower did not reach/prove the correct light-off speed pro repair	Blower not turning on; Missing or incorrect blower feedback signal; Blower stuck always on	Confirm the boiler has power; Try one single reset
Lockout 138	Flame too low – flame signal below the required threshold during operation pro repair	Blocked venting / air-inlet; Fouled or faulty flame sensor	Try one single reset; if it returns, the unit needs service
Lockout 174	Safety relay feedback incorrect (often a failing limit switch in the ILK / interlock circuit) pro repair	Failing limit switch in the ILK circuit (internal LWCO or external limit between R and LIM); Hardware failure of the SOLA controller	Check the boiler system pressure gauge (low water can trip the LWCO); Try one single reset
Alert 248	CH outdoor temperature was invalid – outdoor reset sensor not detected (informational alert, not a lockout) DIY-checkable	Outdoor sensor not connected (the CHS is factory-shipped with Outdoor Reset enabled)	No action needed for heating to run; have a technician connect an outdoor sensor or disable outdoor reset
Loc 01	No flame detected after five ignition attempts pro repair	Incorrect gas supply pressure; No ignition spark / wrong electrode position or gap; Insufficient gas	Confirm the gas supply is turned on and other gas appliances work; Confirm the boiler has power; Press the RESET key once; if it fails again, call a technician
Loc 02	Gas valve not supplied before ignition try (a safety-chain / limit device is open) pro repair	Low-water cut-off (LWCO) open; Flue blocked pressure switch open; High-limit temperature switch open	Check the boiler system pressure gauge for low water/low pressure; Press the RESET key once; if it returns, call a technician
Loc 03	Gas valve lost cable connection during firing pro repair	Interrupted wiring between gas valve and control board; Faulty gas valve or control board	Press the RESET key once; if it returns, call a technician
Loc 04	Gas valve relay not closing pro repair	Interrupted wiring between gas valve and control board; Faulty gas valve or control board	Press the RESET key once; if it returns, call a technician
Loc 05	Gas valve circuit fault (a safety-chain / limit device is open) pro repair	Low-water cut-off (LWCO) open; Flue blocked pressure switch open; High-limit temperature switch open	Check the boiler system pressure gauge for low water/low pressure; Press the RESET key once; if it returns, call a technician
Loc 06	Safety relay open error pro repair	Power control board fault	Press the RESET key once; if it returns, call a technician
Loc 07	Safety relay closed error pro repair	Power control board fault	Press the RESET key once; if it returns, call a technician
Loc 11	Blocking error active for over 20 hours (the underlying blocking 'Err' must be read and resolved) pro repair	A blocking error condition has persisted; press RESET to see the underlying blocking-error reference	Press the RESET key once; if it returns, call a technician to read and resolve the underlying error
Loc 12	Fan (blower) error pro repair	No 120VAC power to the fan; No PWM control signal to the fan; Faulty fan	Confirm the boiler has power; Press the RESET key once; if it returns, call a technician
Loc 27	Flame present with closed gas valve pro repair	Gas valve not fully closing (gas valve fault)	No safe homeowner action – this is a gas-valve safety fault; turn off and call a technician
Loc 28	Flame present with closed gas valve pro repair	Gas valve not fully closing (gas valve fault)	No safe homeowner action – this is a gas-valve safety fault; turn off and call a technician
Loc 31	Flame lost five times during one heat demand pro repair	Faulty flame detection electrode; Obstruction on air inlet / flue exhaust system; Air-inlet contamination from combustion gas (flue terminal too close to air-inlet terminal)	Visually check that the outside air-inlet and exhaust terminals are clear of snow, leaves or debris; Press the RESET key once; if it returns, call a technician
Err 54	Flame detected in a state in which no flame is allowed to be seen (blocking error – permanent) pro repair	Power control board fault	No safe homeowner action – this is a permanent blocking error; call a technician
Err 55 / 56 / 57 / 58 / 59	Low water pressure error (blocking error) pro repair	Low water/pressure in the heating system; Faulty pressure sensor	Check the system pressure gauge – if low, a technician can top up the system to the correct pressure; No homeowner action beyond checking the gauge
Err 60	High flue gas temperature error (blocking error) pro repair	Combustion efficiency lower than 88% (flue gas / water side of heat exchanger fouled); Faulty flue gas temperature sensor	No safe homeowner action – the unit needs cleaning/service; call a technician
Err 61	Return temperature higher than supply (burning) temperature – sensor fault pro repair	Temperature sensor out of specification / faulty	No safe homeowner action – sensor diagnosis is a technician task
Err 64	No correct frequency signal, no correct ground connection, or no communication with the watchdog pro repair	Supply frequency out of the 55-65 Hz range; Improper ground connection; Power control board fault	Confirm the boiler has power; this is an electrical-supply/grounding issue for a technician or electrician
Err 65	Hot/neutral reversed – supply voltage polarity reversed pro repair	Line and neutral wires reversed at the supply	No safe homeowner action – reversed polarity must be corrected by a technician or electrician
Err 67	Faulty earth (ground) connection pro repair	Missing or poor earth/ground connection to the appliance	No safe homeowner action – grounding must be corrected by a technician or electrician
Err 72 / 73 / 76	Supply / return / DHW temperature sensor open circuit (blocking error) pro repair	Temperature sensor disconnected or out of specification	No safe homeowner action – sensor diagnosis is a technician task
Err 80 / 81 / 84 / 86	Supply / return / DHW / flue temperature sensor shorted (blocking error) pro repair	Temperature sensor shorted or out of specification	No safe homeowner action – sensor diagnosis is a technician task
Err 87	Reset button error – too many reset presses within 60 seconds DIY-checkable	Reset key pressed too many times in a short period	Stop pressing reset; wait, then try a single reset only. If a fault keeps returning, call a technician instead of repeatedly resetting
Err 93	Appliance selection error – control configured for the wrong boiler model pro repair	Incorrect appliance configuration parameter (3000-series parameter)	No safe homeowner action – configuration must be corrected by a technician
Err 114	Too low water flow pro repair	Insufficient water flow through the system; Obstruction in the water system	Check the system pressure gauge for adequate pressure; No further homeowner action – flow problems are a technician task
Err 115	Cascade – boiler master failure pro repair	Master (manager) boiler fault in a multi-boiler cascade system	No safe homeowner action – cascade systems must be serviced by a technician
Err 116	Cascade communication failure pro repair	Bus communication interrupted between cascaded boilers; A cascaded boiler is not working	No safe homeowner action – cascade systems must be serviced by a technician
LWCO / LOW WATER (red light blinking)	Low-water cut-off has locked out the burner (Sentry HydroStat control) – shown as a blinking red Low Water light, not a numbered code pro repair	Low water level in the boiler; Low-water cut-off condition sustained for 30 seconds (manual-reset LWCO mode locks out the burner)	Check the boiler system pressure gauge for low pressure / low water; Do NOT add water until the boiler has fully cooled, and have a qualified heating professional check the system before resuming operation

Slant/Fin boiler codes we get called for most

Lockout 109 or Hold 110 — Ignition failure – failure to prove flame after 3 (CHS) ignition attempts

Typical causes include manual gas shutoff valve closed / insufficient gas pressure; spark cable or flame rod disconnected; blocked venting / air-inlet. A few things are safe to check yourself (Confirm the gas supply is turned on and other gas appliances work; Confirm the boiler has power), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes Lockout 109 or Hold 110 on Slant/Fin boilers throughout Greater Vancouver.

Loc 31 — Flame lost five times during one heat demand

Typical causes include faulty flame detection electrode; obstruction on air inlet / flue exhaust system; air-inlet contamination from combustion gas (flue terminal too close to air-inlet terminal). A few things are safe to check yourself (Visually check that the outside air-inlet and exhaust terminals are clear of snow, leaves or debris; Press the RESET key once; if it returns, call a technician), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes Loc 31 on Slant/Fin boilers throughout Greater Vancouver.

Err 55 / 56 / 57 / 58 / 59 — Low water pressure error (blocking error)

Typical causes include low water/pressure in the heating system; faulty pressure sensor. A few things are safe to check yourself (Check the system pressure gauge – if low, a technician can top up the system to the correct pressure; No homeowner action beyond checking the gauge), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes Err 55 / 56 / 57 / 58 / 59 on Slant/Fin boilers throughout Greater Vancouver.

Lockout or Hold 79 — Outlet high limit – boiler outlet water temperature exceeded the high-limit setpoint (factory 200F / 93C)

Typical causes include ch or dhw setpoint plus hysteresis exceeds the high-limit setpoint; ch or dhw pump problem / insufficient flow; incorrect outlet high limit or high-limit response setting. A few things are safe to check yourself (Check that the heating system has adequate water pressure on the gauge; Confirm the thermostat is not calling for an unreasonably high temperature), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes Lockout or Hold 79 on Slant/Fin boilers throughout Greater Vancouver.

Is it safe to keep running a Slant/Fin boiler with a fault code?

Most Slant/Fin 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.

Slant/Fin boiler repair across Greater Vancouver

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

Slant/Fin boiler service areas

We repair Slant/Fin boilers across Greater Vancouver and the Fraser Valley, including:

Slant/Fin boiler error code FAQs

Can I reset my Slant/Fin 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 Slant/Fin Hold 27 code mean?

On Slant/Fin boilers, Hold 27 commonly indicates flame sensor shorted to ground detected (a flame circuit short can show up as a flame circuit timeout). 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 Slant/Fin boilers you didn’t install?

Yes. HeatLand is brand-agnostic and services Slant/Fin 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 Slant/Fin 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 Slant/Fin boiler repair cost in Vancouver?

It depends on the fault. Many Slant/Fin 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: