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HTP · Error codes

HTP Elite Ultra 2 P2 — Anti - Legionella Function not Completely Finished

2 P2

InformationalHTP Elite Ultra (ELU) boilers and combis (group fault codes, manual 420010970305)

Anti - Legionella function not completely finished. Tank sensor improperly installed (ensure fully inserted into the well in the proper location); faulty wiring (check the wiring to the tank sensor for water or corrosion); faulty tank sensor (check the sensor resistance against the temperature resistance chart, replace the sensor); diverting valve failure (no check valves or pumps other than indicated in the plumbing diagram; turn the power off and back on and observe the valve - the shaft should extend and retract ~3/8" several times while the boiler boots up). The table classifies it as Warning.

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Applies to

This sensor 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.

Controller: ELU control (group fault codes). Source manual: 420010970305 (LP-700) (2023-01).

Why a code is not a diagnosis

A sensor code usually means the sensor, its wiring or its mounting is faulty; the physical condition the sensor measures (temperature, pressure, flow) may be perfectly normal.

Safe things to observe

  • Note the code; there is no homeowner-accessible check for sensor circuits.
  • If the appliance still runs, watch whether the code returns and report it when you call.

Do not

  • Do not open the appliance to test or replace sensors yourself.

How professional service helps

  1. A technician measures the sensor and harness against the manual's values and replaces the faulty component.
  2. 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.

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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.

Service for this alert

  • Gas Boiler Repair

    Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…

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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.

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Related

Sources and verification

Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.

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