Rather than memorizing a specific code, it helps far more to understand the handful of categories nearly every fault falls into.
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Quick answer
Noritz boiler fault codes generally fall into a small number of categories: ignition faults, flame-loss or flame-sensing faults, venting or exhaust restrictions, water flow or pressure faults, over-temperature conditions, and sensor faults. The exact code shown on your unit's display should always be checked against the manual for your specific model, since numbering can vary between product lines and revisions, but the diagnostic path a licensed technician follows is largely the same across categories: confirm the affected system, test the relevant components directly, and correct the underlying cause rather than only clearing the fault.
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Manufacturers revise their fault code numbering across product lines and over time, so a code that means one thing on an older unit can mean something different on a newer model, and Noritz's own documentation is the authoritative source for what a specific code on your specific model means. What stays consistent is the underlying category of problem the fault is reporting, which is far more useful for a homeowner to understand than a numeric lookup table that may not match your exact unit.
When you call for service, having the exact code visible on the display, along with when it appeared and what the boiler was doing at the time, is genuinely useful information for the technician even before they check the manual against your model.
| Category | What it generally means | Typical next step |
|---|---|---|
| Ignition fault | The burner attempted to light but did not establish a flame within the expected window | Check gas supply, igniter, and ignition control |
| Flame loss or flame-sensing fault | A flame was established but then lost, or the sensor could not confirm it reliably | Inspect and clean or replace the flame sensor |
| Venting or exhaust fault | The control system detected a restriction or problem in the intake or exhaust path | Inspect vent terminals and piping for blockage or damage |
| Flow or pressure fault | Water is not circulating correctly or system pressure is outside the acceptable range | Check circulator, pressure, and any air in the system |
| Over-temperature fault | The unit sensed a temperature beyond its safe operating range | Check circulation and the relevant temperature sensor |
| Sensor fault | A specific sensor is reporting an implausible or out-of-range reading | Test the sensor and its wiring directly |
Write down the exact code shown, note whether it appeared immediately at start-up or partway through a heating cycle, and note any accompanying sounds or smells. A single reset is usually reasonable to try once. If the fault returns immediately or repeatedly, further resets will not resolve an underlying hardware or venting issue and can, in some situations, mask the real problem or delay a proper fix.
Never bypass a safety lockout by holding down a reset button repeatedly or by disabling a safety switch, since these controls exist specifically to prevent unsafe combustion or venting conditions.
The technician confirms the exact code against the documentation for your specific model, then tests the components associated with that category directly rather than assuming a single likely cause. An ignition fault, for example, involves checking gas supply pressure, the igniter itself, and the ignition control board, since any of the three can produce a similar-looking fault. This methodical approach is why DIY code lookups online, which are often written for a different model or a different revision of the control board, can send a homeowner down the wrong path.
Safety note
Any diagnosis or repair on a gas-fired boiler must be carried out by a Technical Safety BC licensed gas fitter, since the combustion, venting, and control systems are all connected. If you ever smell gas, hear a hissing sound near a gas line, or notice soot or a burning odour near the unit, leave the home immediately and call FortisBC at 1-800-663-9911 from a safe location.
General category information is useful, but the exact meaning of a specific code depends on your model and its control board revision, so the manual for your exact unit, or a licensed technician, is the reliable source.
A single reset is generally reasonable to try. If the fault returns immediately or keeps recurring, stop resetting and call a technician, since repeated resets can mask an underlying safety issue.
Multiple different codes appearing over time can point to a single root cause, such as marginal gas supply or a failing control board, that manifests differently depending on conditions. This pattern is worth mentioning to your technician.
Not necessarily broken permanently. Many faults are the control system correctly responding to a temporary condition, such as low pressure after a bleed, and clear once that condition is corrected.
Yes, along with when it appeared and what the unit was doing. This information speeds up diagnosis considerably compared with just saying the boiler stopped working.
Indirectly. A cold snap increases how hard the system works, which can expose a marginal circulator, a partially restricted vent, or borderline gas pressure that was tolerable in milder conditions.
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