NTI Trinity FTVN 3 03 — PCB Internal Error
3 03
PCB internal error. The PCB reported an internal error; listed causes are water pressure sensor wiring damaged or shorted and a power problem or defective PCB. The table classifies it as Blocking (Auto Reset).
Applies to
This low-water or pressure protection code is displayed by the FTVN Series I control on FTVN Series I models (FTVN085, FTVN110, FTVN150, FTVN199 and combis FTVN110C, FTVN150C, FTVN199C), as documented in FTVN Series I Installation Startup Maintenance Instructions, doc 420011303800 Rev 2.28.23, Part 13-B Boiler Error Codes (420011303800 Rev 2.28.23). Codes can differ between controller generations, so always check the manual that matches your unit.
- NTI Boilers Trinity FTVN
- NTI Trinity FTVN085
- NTI Trinity FTVN110
- NTI Trinity FTVN150
- NTI Trinity FTVN199
- NTI Trinity FTVN110C
- NTI Trinity FTVN150C
- NTI Trinity FTVN199C
Controller: FTVN Series I control. Source manual: 420011303800 Rev 2.28.23 (2023-02-28).
Why a code is not a diagnosis
A water-pressure or low-water code can mean a genuine leak or empty system, a failed expansion tank, a faulty fill valve, or a sensor problem. The appliance does not distinguish these.
Safe things to observe
- Read the pressure gauge and compare it with the normal cold-system pressure your installer set.
- Look for drips or wet spots near the appliance, pipes and the relief-valve discharge.
Do not
- Do not keep re-pressurizing a system that keeps losing water.
- Do not cap a relief-valve discharge pipe.
How professional service helps
- A technician finds and repairs the leak, checks the expansion tank and fill assembly, and verifies the sensor circuit.
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.
Water pressure sensor
The water pressure sensor is the electronic gauge that tells a modern boiler's control how much pressure the heating loop is under.
What a technician checks →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 NTI Boilers Trinity FTVN.
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
- FTVN Series I Installation Startup Maintenance Instructions, doc 420011303800 Rev 2.28.23, Part 13-B Boiler Error Codes · 420011303800 Rev 2.28.23 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.