HVACopediaNTI · Boiler
4 12 Room sensor open or short circuit, Zone 2
What the control is telling you
Zone 2 room sensor circuit fault. Auto reset.
Applies to: TRX150
Models that show this code
5 models in TRX
Other codes on the same units
- 03 07 PCB internal error
- 03 09 Gas relay check failed
- 3 P9 Scheduled maintenance: call for service
- 4 11 Room sensor open or short circuit, Zone 1
- 4 13 Room sensor open or short circuit, Zone 3
- 4 30 Detected accessory wired to BUS connection
- 4 31 Code 431 (no description printed)
- 05 01 Ignition lockout after 3 failed attempts
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Source: NTI TRX150 manual, p. 91. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.