A Laars boiler's fault indicator points to one of a handful of general categories, and knowing the category helps a homeowner describe the problem accurately before service.
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Quick answer
Laars boiler fault indicators generally fall into a small number of categories: ignition failure, loss of flame signal, restricted venting or combustion air, low or high water pressure, and sensor or wiring faults. The exact indicator display and its precise meaning differ by model and control board generation, so the owner's manual or nameplate reference for your specific unit is the accurate source rather than a generic code list. A licensed gas fitter uses the indicator as a starting point, then confirms the actual cause with combustion analysis and testing.
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Laars has produced multiple boiler platforms over the years with different control boards, and fault indicator displays, whether a blinking light pattern, a two-digit code, or a text message on a newer control, are specific to the model and control board revision installed in your home. A code that means one thing on an older platform can mean something different on a newer one. Rather than publish a code table that might not match your actual unit and could lead to a wrong assumption, the more reliable approach is to understand the general categories these indicators represent and confirm the exact meaning against your unit's manual or nameplate.
| Category | What it generally means | Typical underlying causes |
|---|---|---|
| Ignition failure | Boiler could not establish a flame within its attempt window | Gas supply issue, fouled electrode, burner obstruction |
| Flame loss | Flame signal dropped out after ignition succeeded | Dirty flame sensor, incorrect gas pressure, draft disturbance |
| Venting / combustion air | Restricted intake or exhaust airflow detected | Blocked terminal, snow or debris accumulation, failing fan |
| Water pressure (low or high) | System pressure outside the acceptable operating range | Slow leak, waterlogged expansion tank, recent bleeding of radiators |
| Sensor / wiring | A temperature or pressure sensor reading implausible values | Failed sensor, damaged wiring, loose connector |
It is common for the same general fault category, such as flame loss, to be represented by a different indicator sequence depending on which Laars platform and control board generation is installed. Because of this, general fault information is commonly documented at the category level; the exact indicator sequence and any model-specific reset procedure should always be verified against the manual for your specific unit rather than assumed from a general list. A technician arriving on site will confirm the exact model and control board before interpreting the indicator, which is the accurate way to approach it.
A proper diagnosis goes beyond reading the fault indicator: it includes a combustion analysis, a check of incoming and manifold gas pressure, an inspection of the venting and combustion air path, and testing of the relevant sensors and wiring. The fault indicator narrows down where to start, but the actual cause is confirmed with instruments, not by guesswork based on the display alone. Because this involves gas combustion equipment and its safety controls, diagnosis and repair must be carried out by a Technical Safety BC licensed gas fitter.
Safety note
If you ever smell gas, hear a hissing sound near the unit, or notice soot, a burning smell, or symptoms like headaches and drowsiness near the appliance, leave the home immediately and call FortisBC at 1-800-663-9911 from a safe location before doing anything else. Diagnosing or repairing a gas boiler fault must be done by a Technical Safety BC licensed gas fitter.
Laars has used multiple control board generations across its boiler platforms, and the same fault category can be represented by different indicators depending on which one is installed. Category-level information is reliable across the board; exact codes should be verified against your unit's manual.
Ignition and flame-related faults are among the most commonly seen categories, generally tied to gas supply, electrode condition, or flame sensor cleanliness, though the exact frequency depends on the individual system and its maintenance history.
You can, but results found online may reference a different model or control board generation than the one in your home. The manual or nameplate for your specific unit, or a technician who confirms the model on site, is the accurate source.
One reset is generally reasonable after checking pressure and the outdoor vent terminal. If the same fault returns quickly, stop resetting and have a licensed technician diagnose the actual cause instead.
Not always immediately, since pressure can drop slightly over time from normal air release, but pressure that keeps recurring as low after topping up does point toward a leak that a technician should locate.
Yes, noting the exact display, any blink pattern or code, and when it appeared helps the technician prepare and can speed up the diagnostic visit, even though the final confirmation will come from on-site testing.
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