Lochinvar Knight Gas Pressure SW — Gas Pressure Switch Contacts are Open
Gas Pressure SW
Gas pressure switch contacts are open. The gas pressure switch contacts on the Low Voltage Connection Board are open, so check for a loose or misplaced jumper or a device wired across the gas pressure switch terminals on that board. The table classifies it as Lockout (manual reset).
Applies to
This electronics fault code is displayed by the SMART SYSTEM control on Knight fire-tube boilers (KHB floor 055–285 and WHB wall 055–399), as documented in Knight Service Manual, doc 100305279 Rev E — Table 3-4 fault codes (KHB floor; the WHB service manual Rev G prints the same table) (100305279 Rev E). Codes can differ between controller generations, so always check the manual that matches your unit.
- Lochinvar Knight Floor Mount (KHB)
- Lochinvar Knight Wall Mount (WHB)
- Lochinvar Knight KHB055
- Lochinvar Knight KHB085
- Lochinvar Knight KHB110
- Lochinvar Knight KHB155
- Lochinvar Knight KHB199
- Lochinvar Knight KHB285
- Lochinvar Knight WHB055
- Lochinvar Knight WHB085
- Lochinvar Knight WHB110
- Lochinvar Knight WHB155
- Lochinvar Knight WHB199
- Lochinvar Knight WHB285
- Lochinvar Knight WHB399
Controller: SMART SYSTEM control. Source manual: 100305279 Rev E (2024-04).
Why a code is not a diagnosis
An electronics code points at the control board, memory or firmware. It is often triggered by poor incoming power or voltage backfeed from other wiring rather than by the appliance itself.
Safe things to observe
- Note the code and whether it appeared after electrical work or a power event.
Do not
- Do not open the control module.
- Do not repeatedly power-cycle to clear a recurring board code.
How professional service helps
- A technician checks supply voltage and grounding, follows the manual's reset sequence and replaces the module only if the code returns.
- Combustion and safety devices are verified with an analyser and the manufacturer's procedure after any repair.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Parts and service
Parts commonly involved
These parts appear in the documented text for this alert. A code reports a condition, not a failed part — a technician confirms the cause by testing before anything is replaced.
Gas pressure switch
A gas pressure switch proves that gas pressure at the boiler is within a safe range before the burner is allowed to fire, and it shuts the burner…
What a technician checks →
Service for this alert
- Gas Boiler Repair
Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…
- Emergency Boiler Repair
Priority gas boiler repair for homes and buildings in Greater Vancouver with no heat, no hot water, a locked-out boiler or a leak.
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for Lochinvar Knight Floor Mount (KHB) and Lochinvar Knight Wall Mount (WHB).
Frequently asked questions
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- Knight Service Manual, doc 100305279 Rev E — Table 3-4 fault codes (KHB floor; the WHB service manual Rev G prints the same table) · 100305279 Rev E · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.