HTP Elite Ultra 3 02 — Communication Error Gp - Giu
3 02
Communication error GP - GIU. Wiring between PCB and display damaged/disconnected (check the wire connection between the PCB and the display for damage, corrosion or other problems); power problem/defective PCB - test for proper voltage and grounding at the electrical supply; switch the boiler OFF and ON at the main electrical power supply; if the problem persists replace the main PCB. The table classifies it as Blocking (Auto Reset).
Applies to
This electronics fault code is displayed by the ELU control (group fault codes) on ELU models (ELU-85WBN through ELU-199WCN), as documented in Elite Ultra (ELU) Installation Manual (Table 32 fault codes), 420010970305 / LP-700 (1.24.23) — 150/199 sizes in 420011303900 (420010970305 (LP-700)). Codes can differ between controller generations, so always check the manual that matches your unit.
- HTP Elite Ultra (ELU)
- HTP ELU-85WBN
- HTP ELU-120WBN
- HTP ELU-120WCN
- HTP ELU-150WBN
- HTP ELU-150WCN
- HTP ELU-199WBN
- HTP ELU-199WCN
Controller: ELU control (group fault codes). Source manual: 420010970305 (LP-700) (2023-01).
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.
Control board / PCB
The control board — also called the PCB, or printed circuit board — is the boiler's main computer.
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 HTP Elite Ultra (ELU).
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
- Elite Ultra (ELU) Installation Manual (Table 32 fault codes), 420010970305 / LP-700 (1.24.23) — 150/199 sizes in 420011303900 · 420010970305 (LP-700) · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.