Lochinvar Boiler Error Codes

A plain-English reference to 10 common Lochinvar fault codes — what each means, what causes it, and when to call a licensed BC gas technician.

Lochinvar boilers (Knight and WHN, with the SMART System control) show a descriptive fault on the touchscreen when a safety circuit trips. This reference explains the common Lochinvar faults, their likely causes, and why ignition, flame, gas and venting faults must be diagnosed by a licensed BC gas technician.

Smell gas? Leave the building immediately and call 911 or FortisBC at 1-800-663-9911 from outside. Never bypass a safety lockout or attempt gas work yourself — in BC it must be done by a licensed gas fitter.

Ignition fault

Lochinvar Ignition FailureIgnition Failure

Flame failure

Lochinvar Flame LossFlame Loss / Flame Circuit Fault

Air-pressure / venting fault

Lochinvar Air Pressure FaultAir-Pressure / Blocked-Vent Fault Lochinvar Stack High LimitStack (Flue) High Limit

Over-temperature / high-limit

Lochinvar Outlet High LimitOutlet High-Limit / Over-Temperature

Temperature-sensor fault

Lochinvar Inlet Sensor FaultInlet Sensor Fault Lochinvar Outlet Sensor FaultOutlet Sensor Fault

Water-flow / circulation fault

Lochinvar Flow Switch OpenFlow Switch Open / Low Flow

System water-pressure fault

Lochinvar Low WaterLow Water

Combustion-fan fault

Lochinvar Blower FaultBlower Fault

Lochinvar error codes — FAQ

Why is my Lochinvar boiler showing an error code?

Lochinvar boilers display a fault code when a safety circuit detects a problem — for example with ignition, flame, water flow, temperature or venting. The code points to the affected system. The boiler shuts down to protect itself; a licensed technician then diagnoses the true root cause before repair.

Can I just reset my Lochinvar boiler?

A single reset after a one-off event is usually fine, but repeated resets without fixing the cause can be unsafe — especially for ignition, gas and venting faults — and can cause further damage. If the code returns, switch the boiler off and call GasBoilers.ca at 604-359-1081.

Do you repair all Lochinvar boiler models in Greater Vancouver?

Yes. Our Red Seal–certified, gas-licensed technicians service Lochinvar Knight, WHN and SMART System series across Vancouver, Burnaby, Surrey, Richmond, the Tri-Cities and the rest of Greater Vancouver. Same-day appointments are often available.

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Get your Lochinvar boiler back up and running

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