Lennox GCWB95 83-84-85 — Communication Problem Between Boiler Board and Control Unit
83-84-85
Communication problem between boiler board and control unit. A communication problem between the boiler board and the control unit, with a probable short circuit on the wiring; the manual directs calling an authorized service technician. The table classifies it as Error.
Applies to
This electronics fault code is displayed by the GCWB95 control (numeric error display with RESET) on GCWB95 models (GCWB95W-150, GCWB95W-205 wall hung combi and GCWB95F-150 floor mount combi), as documented in Lennox GCWB95 User's Information Manual, PN 240012894 Rev. A [04/15/2020], Section 3.6 error messages (models GCWB95W-150, GCWB95W-205 wall hung combi and GCWB95F-150 floor mount combi) (240012894 Rev. A). Codes can differ between controller generations, so always check the manual that matches your unit.
Controller: GCWB95 control (numeric error display with RESET). Source manual: 240012894 Rev. A (2020-04-15).
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.
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
- Lennox GCWB95 User's Information Manual, PN 240012894 Rev. A [04/15/2020], Section 3.6 error messages (models GCWB95W-150, GCWB95W-205 wall hung combi and GCWB95F-150 floor mount combi) · 240012894 Rev. A · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.