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NTI · Boiler

05 02 Flame detected with gas valve closed

High severity TRX

What the control is telling you

Flame signal is present while the gas valve is closed. Auto reset.

Applies to: TRX150

Likely causes

  • Faulty flame detection electrode
  • Faulty main PCB

Test and repair steps

  1. If it returns, disconnect the flame detection electrode, then press Reset.
  2. If the error does not return, replace the flame detection electrode.
  3. If it returns again, replace the main PCB.

Models that show this code

5 models in TRX

TRX085TRX110CTRX150TRX199TRX199C

Other codes on the same units

  • 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
  • 05 04 10 flame lifts in one operating cycle
  • 5 P1 1st ignition failed
  • 5 P2 2nd ignition failed
  • 5 P3 Flame loss during run

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Source: NTI TRX150 manual, p. 86. 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.