Lochinvar Knight XL Service Blk — Outlet Temperature Exceeded 185°f While the Unit is in Service Mode
Service Blk
Outlet temperature exceeded 185°F while the unit is in Service Mode. While the unit is in Service Mode the outlet temperature has exceeded 185°F, so establish a heating load to remove the heat from the boiler loop, verify the system is full of water and all air is purged, verify the boiler is piped properly, and check the boiler pump operation and size.
Applies to
This fault code is displayed by the Knight XL control (text faults) on Knight XL models (KBX0400 through KBX1000), as documented in Knight XL (KBX) Service Manual, 100383164 Rev C — Table 3-4 fault codes (100383164 Rev C). Codes can differ between controller generations, so always check the manual that matches your unit.
- Lochinvar Knight XL Commercial (KBX)
- Lochinvar Knight XL KBX0400
- Lochinvar Knight XL KBX0500
- Lochinvar Knight XL KBX0650
- Lochinvar Knight XL KBX0800
- Lochinvar Knight XL KBX1000
Controller: Knight XL control (text faults). Source manual: 100383164 Rev C (2025-10).
Why a code is not a diagnosis
The code reports the condition the control detected; the underlying cause must be confirmed on site by a licensed technician using the manufacturer's procedure.
Safe things to observe
- Note the exact code, when it appears and what the appliance was doing.
- If the appliance has stopped, call a technician rather than repeatedly restarting it.
- If you smell gas, stop, go outside and call your gas utility's emergency line or 911 before anything else.
Do not
- Do not ignore a code that returns after a reset.
How professional service helps
- A licensed technician diagnoses the cause with the manufacturer's test procedure.
- 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.
Circulator pump
The circulator is the pump that moves heated water from a boiler out to the radiators, baseboards or in-floor loops and back again.
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…
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for Lochinvar Knight XL Commercial (KBX).
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 XL (KBX) Service Manual, 100383164 Rev C — Table 3-4 fault codes · 100383164 Rev C · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.